Information on COVID-19 epidemiology is continually evolving. For the most up-to-date data on COVID-19 cases, visit:

• Global: https://health-infobase.canada.ca/covid-19/international/
• Canada: https://health-infobase.canada.ca/covid-19/
• British Columbia: http://www.bccdc.ca/health-professionals/data-reports/respiratory-virus-data
  

The COVID-19 pandemic has caused significant morbidity and mortality, as well as social and economic disruption in Canada and worldwide. Since their introductions, COVID-19 vaccines have shown to be very effective at preventing severe disease, including hospitalization and death due to COVID-19. COVID-19 vaccination protects not only the person being vaccinated, but also people around them, including those who are unable to get the vaccine. The more people in a community who are immunized and protected from COVID-19, the harder it is for COVID-19 to spread. Furthermore, people who are vaccinated and have been infected with SARS-CoV-2 have additional protection against post-COVID-19 condition (PCC). The available evidence suggests there is a positive relationship between the number of doses received and level of protection against PCC.¹ Receiving the updated COVID-19 vaccine is especially important during the fall, when increased activity of respiratory viruses is observed. COVID-19 disease can compound the impact on the health system of other fall and winter viruses.¹

1. National Advisory Committee on Immunization (NACI) Guidance on the use of COVID-19 vaccines during the fall of 2024. 2024 [cited 2024 Jul 8]. Available from: https://www.canada.ca/en/public-health/services/publications/vaccines-immunization/national-advisory-committee-immunization-guidance-covid-19-vaccines-fall-2024.html‎

Factors that allowed COVID-19 vaccines to progress quickly include advances in vaccine development technology, government funding and purchase commitments, international collaboration among health professionals, researchers, industry and governments to develop the vaccines, rapid recruitment of participants for clinical trials, and streamlined vaccine approval processes by the regulatory body at Health Canada. Canada’s rigorous vaccine approval process has remained in place to assess COVID-19 vaccines.

As for all vaccines and treatments that are authorized in Canada, Health Canada reviews the evidence and scientific data and decides whether to authorize the COVID-19 vaccine and will only do so when the evidence shows that the vaccine:

• is safe, effective and of good quality and
• demonstrates that the benefits outweigh the known and potential risks
  

Health Canada also has processes in place to share information with/from other countries’ regulatory bodies including the US Food and Drug Administration and the European Medicines Agency.

Once a vaccine is approved, vaccine safety and effectiveness are continuously monitored to detect rare serious or unexpected side effects.

The Biologic and Radiopharmaceutical Drugs Directorate (BRDD), which is part of Health Canada, supervises all aspects of vaccine production and quality control throughout the vaccine’s lifecycle. When a manufacturer develops enough scientific and clinical evidence of a vaccine’s safety, efficacy, and quality, they file a complete package of information that is submitted to BRDD for market authorization. A submission contains data from scientific studies, including laboratory and clinical studies, and information about the manufacturing process, including the manufacturing facility and manufacturing method. BRDD thoroughly reviews the submission to determine whether the benefits of a vaccine outweigh any potential risks. BRDD also reviews procedures for the manufacturer’s safety monitoring and any plans to minimize any identified risks. In addition, BRDD may visit the manufacturing site to evaluate the manufacturing process’ quality and make sure the manufacturer can carry out the necessary quality controls for the vaccine.

The expedited review performed for COVID-19 vaccines has been possible because of a number of administrative changes to the process. These have included allowance of submission of data when available rather than the sponsor needing to wait until the entire data package is complete prior to submission. As well, for approval of these vaccines in Canada and many countries, there has been allowance for a shorter period of follow-up of people enrolled into the phase 3 clinical trials, whereas for non-pandemic vaccines, that follow-up period is typically upwards of one year. As a result, the clinical trials will continue to accrue cases and safety information for up to two years following immunization. Results from these studies will be reported in the future and will provide additional information about issues such as duration of protection from the vaccine(s).

Additional Health Canada information is available at: Vaccines and Treatments for COVID-19: Progress and Interim Order Respecting the Importation, Sale and Advertising of Drugs for Use in Relation to COVID-19.

For an effective conversation about COVID-19 vaccines, we can start from a place of compassion and understanding. Patients consistently rank healthcare providers as their most trusted source for vaccine information. Be transparent about the latest vaccine(s) information, reassure that we have a robust vaccine safety system in Canada, and emphasize vaccines’ role to protect recipients and the people around them. Your willingness to listen to the patients’ concerns will play a significant role in building trust in you and your recommendation. If a patient has concerns or questions, this doesn’t necessarily mean they won’t accept a COVID-19 vaccine. Sometimes patients simply want your answers to their questions. Once you’ve answered their questions, let them know that you are open to continuing the conversation. Encourage your patients to schedule another appointment or go to the BCCDC or ImmunizeBC websites for more information about COVID-19 vaccination. Continue the conversation about COVID-19 vaccination during future visits.

‎Canada has a system of local, provincial, and national surveillance to carefully monitor adverse events following immunization and detect any vaccine safety concerns. Once a vaccine is approved, its safety is continuously being monitored as long as it is used. In most provinces and territories, including BC, health care providers are legally obliged to report all serious and unexpected adverse events following immunization to the medical health officer. Every serious or concerning event is reported to the BC Centre for Disease Control (BCCDC). These reports are reviewed at BCCDC and also sent to the Public Health Agency of Canada system called the Canadian Adverse Events Following Immunization System (CAEFISS), as are reports from all provinces and territories. Additional monitoring for adverse events is being done through a system called CANVAS (Canadian National Vaccine Safety Network) through which recipients of the vaccine can enrol to self-report adverse events following receipt of the vaccine, with serious events being reported on to the regional health authority.

Vaccine safety is also monitored at the international level. The World Health Organization’s International Drug Monitoring Program collects reports from over 75 countries and uses these global data to monitor for any vaccine safety concerns. In addition, all vaccine manufacturers must report serious adverse events of which they become aware, in Canada or internationally, to Health Canada. For COVID-19 vaccines, manufacturers are expected to implement enhanced monitoring activities.

In B.C., reports on adverse events following COVID-19 immunization are available on BCCDC's COVID-19 Vaccine Safety page.

The national reports on adverse events following COVID-19 immunization are available on Health Canada’s Reported Side Effects Following COVID-19 Vaccination in Canada page.

More information about the Canadian vaccine safety surveillance system is contained in the Canadian Immunization Guide, Part 2 – Vaccine Safety, Vaccine safety and pharmacovigilance.

‎Vaccine providers should refer to the BC Immunization Manual, Part 5 – Adverse Events Following Immunization for criteria on reporting adverse events following immunization (AEFI), and report AEFIs to the regional health authority. Information on reporting can be found on the BCCDC’s Surveillance Forms page under Adverse Events Following Immunization. There is a short version of the AEFI form available for health care providers. Those providers who work in public health still need to use the long form.

For more information and details on how to report an AEFI in B.C., go to the BCCDC Reporting Adverse Events Following Immunization: For BC Community Vaccine Providers.

The National Advisory Committee on Immunization (NACI) recommends the most recently updated COVID-19 vaccines (i.e., the vaccines targeting Omciron JN.1 lineage, JN.1 and KP.2 strains) for fall 2024.¹ In Canada, the updated Moderna and Pfizer-BioNTech vaccines for fall 2024 target the KP.2 strain. The approved Novavax vaccine targets the JN.1 strain. These formulations targeting more recent Omicron sublineages are expected to provide better protection against current circulating variants.

Review COVID-19 Vaccine Eligibility in Part 4 -Biological Products of the BC Immunization Manual for additional details.

Real world evidence suggests moderate to high vaccine effectiveness at preventing severe illness, such as hospitalization and death, which is sustained out to at least 6 months in most populations aged 12 years and older, including in older and frail populations. There is some decline in overall effectiveness noted in older adults (such as those 80 years of age and over) and residents in long term care homes over time, although protection against severe outcomes appears to be more durable than protection against infection.² There are limited follow-up studies evaluating VE following vaccination with updated COVID-19 vaccines during the fall/winter 2023-2024 vaccination campaigns; however, emerging evidence suggests that waning VE against symptomatic infection may occur in the first 4 months, similar to previous COVID-19 vaccines.¹

In the current epidemiological context of the COVID-19 pandemic, individuals who have developed immunity against COVID-19 have done so through one of the following circumstances:

• Infection-induced immunity which describes the immune protection in an unvaccinated individual after one or more SARS-CoV-2 infections.
  
• Vaccine-induced immunity which is the immunity achieved by an individual who has not been infected with SARS-CoV-2 but has a primary series of any COVID-19 vaccine or has received a booster vaccination.
  
• Hybrid immunity is defined as the immune protection in an individual who has had one or more doses of a COVID-19 vaccine and experienced at least one SARS-CoV-2 infection before or after receiving COVID-19 vaccine.³

Evidence demonstrates that hybrid immunity may provide superior protection against COVID-19 compared to vaccination or previous infection alone, particularly when hybrid immunity is in the context of a recent infection.^{1, 4} In a vaccinated individual, infection acts as a “dose” to increase neutralizing antibodies and may induce broader antibodies that respond better to variants. Evidence is emerging that vaccinated individuals who had been infected also demonstrate increased T cell proliferation and broadened T cell responses⁵ as well as increased neutralizing antibodies, compared to those without a history of infection.⁶ It is also noted that the level of B cell response significantly increases when individuals who have received two or three doses of COVID-19 vaccine also had a prior Omicron infection, compared to those who received two or three doses of COVID-19 vaccine but had not been infected with the Omicron strain.⁷ Hybrid immunity may provide better protection against reinfection with variants of concern (including Omicron)⁶ and available evidence suggests protection from infection is variant dependent.⁷ It should be noted, however, that infection-induced responses vary much more widely than vaccine-induced, thus reliance on infection-induced immunity alone is risky. Vaccination is still the safest and most reliable way to induce protection against severe COVID-19.⁴

The latest Canadian data on hybrid immunity has identified that adolescents and young adults have the highest proportion of hybrid immunity. In Canada, a greater proportion of older adults have protection from vaccination only and have not been infected as compared to younger ages, while a large proportion of children have been infected but not vaccinated.⁸

A recent systematic review found that the effectiveness of hybrid immunity against hospital admission or severe disease was 97.4% at 12 months with primary series and 95.3% at 6 months with first booster after the most recent infection or vaccination.⁹ This hybrid immunity appears to plateau after 2 doses and does not improve with more (assessed as 3 to 5) doses of vaccine. Hybrid immunity has been observed among those infected in the pre-Omicron and Omicron era; in the period of circulation of the BA.4/5 variants, protection against hospitalization upon reinfection is >90% among individuals with hybrid immunity who have received at least two doses of vaccine.¹⁰

Any of the available, updated age-appropriate COVID-19 vaccines can be used to complete a primary series started with another product and as a subsequent dose in the previously vaccinated, regardless of the platform or manufacturer. When a COVID-19 vaccine is used to complete the primary series started with another COVID-19 vaccine formulation, the previous dose should be counted, and the series need not be restarted.¹¹‎

Yes. COVID-19 vaccines may be given concomitantly (i.e., same day), or at any time before or after non-COVID-19 vaccines (including live and non-live vaccines). If more than one vaccine is administered at a single visit, they should be administered at different injection sites using separate injection equipment. Preferably this is in different limbs, however if the same limb must be used, the injection sites should be separated by at least 2.5 cm (1 inch).²

Co-administration of COVID-19 vaccines with other vaccines is in accordance with NACI recommendations, general best practices for immunization, and is supported by the US Center for Disease Control and Prevention and the World Health Organization.

Data from recent studies also support the co-administration of COVID-19 and influenza vaccines. These studies have found co-administration to be safe and the immune response towards all influenza strains and the SARS-CoV-2 spike protein with co-administration is generally non-inferior to that seen when either vaccine is administered alone.^12-18 There are also data to support the co-administration of COVID-19 vaccine and pneumococcal polysaccharide 23 vaccine.⁵ Most studies that evaluated the concurrent administration of COVID-19 vaccine found no safety issues compared to separate administration. In some studies, increased reactogenicity was noted when COVID-19 and influenza vaccines were given together, compared to just getting the influenza vaccine alone. However, reactogenicity from concurrent administration of influenza and COVID-19 vaccines are comparable to COVID-19 vaccination alone.¹ The adverse events reported were mostly mild-to-moderate and self-limiting.¹⁸

Co-administration has several potential benefits, including improved patient convenience and compliance, simplified immunization schedules, fewer missed opportunities to vaccinate, reduced costs, and logistical advantages.¹⁸ Co-administration reduces barriers to the provision of routine childhood immunizations and seasonal influenza immunization.²

‎No. COVID-19 vaccines do not cause infertility and there is no scientific reason to believe that they will. Recent studies have shown that COVID-19 vaccines do not impact fertility.^{19, 20}

The Society of Obstetricians and Gynaecologists of Canada (SOGC) addresses this online rumour in their recent statement stressing, “there is absolutely no evidence, and no theoretic reason to suspect that the COVID-19 vaccine could impair male or female fertility” and added, that “the widespread social media concern stems from misinformation about the similarities between syncytin-1 (used for placental implantation) and the SARS-CoV-2 spike protein. While the two proteins have several similar amino acids, they remain vastly different. The antibodies produced against the SARS-CoV-2 spike protein would not have cross-reactivity with syncitin-1.”²¹

The minimum age for COVID-19 immunization is 6 months (not 24 weeks). For premature infants, chronological age based on actual birth date should be used as opposed to corrected age.²²‎

‎COVID-19 vaccination among pregnant people remains a priority.²³

Pregnancy is a higher risk period for complications from COVID-19 infection. Pregnant people are more likely to be hospitalized and admitted to intensive care compared to their non-pregnant age-matched peers.^{2, 23} Infants born to mothers infected with COVID-19 are also at higher risk of severe outcomes, including stillbirth, admission to the neonatal intensive care unit, and death.^{23, 24}

Pregnant people with complete or boosted vaccine doses had reduced risk for severe symptoms, complications, and death.

Although the primary indication for administration of COVID-19 vaccination is for maternal protection, IgG antibodies from the pregnant person are transferred to the fetus. This provides passive immunity to the newborn, which may reduce the risk of infection for the infant during their first several months of life. Recent data on hospitalization of children 17 years of age and younger in the US has found hospitalization to be highest amongst children 4 years of age and under. Furthermore, for those 4 years of age and younger, rates of hospitalization were highest among infants younger than 6 months which highlights the importance of passive immunity as there are no COVID-19 vaccines approved for this age group.²⁵ COVID-19 vaccination during pregnancy has not been shown to increase the risk of miscarriage, congenital anomalies, preterm delivery or other adverse perinatal outcomes.^{26, 27}

While the safety and efficacy of the COVID-19 vaccines were not studied in people who were pregnant or breastfeeding in the clinical trials for these vaccines, evidence during the post-marketing period has accumulated. Outcomes in participants who became pregnant during the clinical trials and fetal outcomes are reported through registries, and real-world evidence (mostly with mRNA vaccination) in now available. Both NACI and the Society of Obstetricians and Gynaecologists of Canada (SOGC) have pre-existing general recommendations that inactivated viral vaccines can be safely given in pregnancy. The SOGC recommends that pregnant people, those contemplating pregnancy, and those who are breastfeeding who are at high risk of infection and/or morbidity from COVID-19 should be offered the vaccine.²⁸

‎NACI continues to recommend that COVID-19 vaccines should be offered to people who have previously been infected with SARS-CoV-2. There are no known safety risks with receiving a COVID-19 vaccine after a recent SARS-CoV-2 infection.²⁹ COVID-19 vaccine can be offered to individuals at any time following recovery from SARS-CoV-2 infection.

Although not required, people who recently had SARS-CoV-2 infection (i.e., tested positive for COVID-19 by PCR or rapid antigen test) may consider delaying COVID-19 vaccination by 3-6 months from symptom onset or, for asymptomatic cases, from the time of the positive test. The longer interval between infection and vaccination may result in a better immune response and longer-lasting protection against SARS-CoV-2, and the likelihood of reinfection during this period of time is small. This suggested interval between SARS-CoV-2 infection and COVID-19 vaccination is intended to serve as a guide and is based on the available evidence on the safety, effectiveness and timing of vaccination following infection, immunological principles, and expert opinion.³⁰ However, an individual's biological and social risk factors for exposure (e.g., local epidemiology, circulation of VOCs, living settings) and risk of severe disease should be taken into account when deciding whether to delay vaccination up to 3-6 months after infection.^{30, 31}

‎Currently, all COVID-19 vaccines approved for use in Canada are inactivated vaccines (not live vaccines) and antivirals have no effect on the response to inactivated vaccines. Therefore, clients receiving COVID-19 antiviral treatment can safely receive the COVID-19 vaccine. However, if the client is still experiencing symptoms of the viral illness for which the medication was prescribed, it might be best to delay the immunization so that the cause of any additional or worsening symptoms can easily be determined.

For additional information, see the BC Immunization Manual, Appendix C: Contraindications and Precautions for Immunization.

‎There is a theoretical risk that mRNA vaccines could temporarily affect cell-mediated immunity, resulting in false-negative TST or IGRA test results. However, there is no direct evidence for this interaction. Therefore, in the absence of data and acknowledging the importance of both timely tuberculosis testing and immunization, vaccination with COVID-19 vaccines may take place at any time before, after or at the same visit as the TST or IGRA test. Repeat TST or IGRA (at least 4 weeks post-COVID-19 immunization) of individuals with negative TST or IGRA results for whom there is high suspicion of latent tuberculosis infection may be considered in order to avoid missing persons with TB infection.²

‎Prophylactic oral analgesics or antipyretics (e.g., acetaminophen or non-steroidal anti-inflammatory drugs such as ibuprofen) should not be routinely used before or at the time of vaccination. There is currently no evidence of benefit from administration of oral analgesics for the prevention of immunization injection pain or systemic reactions.² While these medications may be considered for the management of adverse events (e.g., pain or fever, respectively), it is not known whether these may blunt the antibody response to vaccine. This phenomenon has been observed in some studies of other vaccines in children, although its clinical significance is unknown.^32-34 If an individual has taken one of these medications prior to immunization for any reason, they should be immunized as planned.

‎Lymphadenopathy (reactive adenopathy related to the immune response generated by the vaccine) in the regional nodes draining the deltoid area can occur. Such enlarged nodes may be viewed in imaging studies such as mammograms and may be interpreted as abnormal and indicative of potential pathology.

The BC Cancer Agency recommends that scheduled screening mammograms should not be cancelled or delayed because of COVID-19 immunization. Those undertaking imaging within 6 weeks following vaccination should be asked for information about the site of vaccination so that this information can be recorded and considered in the interpretation of the radiograph.³⁵

For those being vaccinated in the context of suspect or known breast malignancy, the vaccine should be given in the contralateral arm for both doses.

It is normal for parents/guardians to have questions about what is best for their children. Healthcare providers continue to be a trusted source for immunization information and as parents/guardians consider the possible risk and benefits of vaccinating their children, healthcare providers can be there to address their questions.

While the majority of children with COVID-19 have mild or asymptomatic disease, some children get severe disease and require hospitalization. Following infection with the SARS-CoV-2 virus, children are also at risk of developing multisystem inflammatory syndrome in children (MIS-C) and may also develop a post-COVID condition also known as long-COVID or post-acute COVID. Unfortunately, we cannot predict which children could have severe outcomes associated with COVID-19.

Emerging data from the US suggests between October 2023 to March 2024 amongst infants, children and adolescents, rates of COVID-19 associated hospitalization to be highest for those 4 years of age and younger. Furthermore, in those 17 years of age and younger, 50% did not have any underlying medical conditions and amongst those with no underlying medical conditions 18% were admitted to ICU. Furthermore, it was noted 95% of those hospitalized had received a fall 2023/24 COVID-19 vaccine.²⁵ This data illustrates that SARS-CoV-2 continues to cause severe illness in children.

Vaccination will provide their child with an additional layer of protection from COVID-19. Vaccinating their child may also help them to feel more comfortable when they are in group settings such as childcare and other activities.

For more information:

• ImmunizeBC provides information for the public on COVID-19 vaccines for children and youth in BC including a Q&A for parents
• Canadian Pediatric Society’s COVID-19 vaccine for children and youth Q&A offers information about COVID-19 vaccination in children including more information about vaccine safety in Canada
• Children’s Hospital of Philadelphia’s website includes the resource Should my child get the COVID-19 vaccine? – a comprehensive Q&A for parents that helps to address misinformation and online rumours about COVID-19 vaccine.
  

‎As indicated in the BC Immunization Manual, Appendix B: Administration of Biological Products (PDF), aspiration prior to injection of a vaccine is no longer recommended as there are no large blood vessels at the recommended immunization sites and aspiration can increase pain resulting from the combined effects of a longer needle-dwelling time in the tissues and shearing action (wiggling) of the needle.^{36, 37} Aspiration was originally recommended for theoretical safety reasons, however the veins and arteries within reach of a needle in the anatomic areas recommended for vaccination are too small to allow an intravenous push of vaccine without blowing out the vessel.³⁷

While there is no evidence to support the need for aspiration, there is no prohibition on aspiration when administering a vaccine. Therefore, to avoid barriers and missed opportunities for COVID-19 immunization, this procedure could be done to accommodate case-by-case requests. However, clients should be informed of the possibility of increased pain and discomfort at the injection site. Providing the rationale for not aspirating with injection may assist the client in making an informed choice on the procedure which may include the following information:

• There is no scientific evidence to support the need for aspiration
• There are no published reports of adverse effects associated with not aspirating
• The deltoid site used for intramuscular injection is not in close proximity to large blood vessels, therefore the possibility of inadvertently hitting a blood vessel is rare
• For aspiration to be effective, it must be sustained for at least 5-10 seconds
• Injection with aspiration is more painful, likely because aspiration, when performed correctly for 5-10 seconds, results in longer contact time between the needle and the tissue and movement of the needle within the tissue during aspiration is expected
• Bleeding at the injection site is common, and does not indicate incorrect injection technique or injection into a blood vessel
  

Oral analgesics or antipyretics may be considered post-vaccination for the management of symptoms attributed to the vaccine (e.g., pain, fever, headache, myalgia) if these cannot be readily tolerated using non-pharmaceutical strategies.

Needle aspiration is performed by pulling back on the plunger (applying negative pressure) of the syringe after inserting the needle into the client and prior to injecting the vaccine and includes the following steps:

• After the needle pierces the skin, use the thumb and forefinger of the non-dominant hand to hold the syringe barrel
• Move the dominant hand to the end of the plunger
• Avoid moving the syringe
• Aspirate by holding the barrel of the syringe steady with your non dominant hand and by pulling back on the plunger with your dominant hand³⁸

Effective aspiration may require 5 to 10 seconds prior to injection; if blood appears in the barrel of the syringe during this time, do not inject the vaccine and withdraw the needle, and properly discard the syringe.³⁹

Source: BCcampus OpenEd

1. National Advisory Committee on Immunization (NACI). Guidance on the use of COVID-19 vaccines during the fall of 2024. 2024 [cited 2024 Jul 8]. Available from: https://www.canada.ca/content/dam/phac-aspc/documents/services/publications/vaccines-immunization/national-advisory-committee-immunization-guidance-covid-19-vaccines-fall-2024/naci-statement-2024-05-03.pdf.

2. Public Health Agency of Canada. Canadian Immunization Guide [Internet]. Evergreen ed. Part 4 - Immunizing Agents: COVID-19 Vaccines. 2023. Available from: https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-4-active-vaccines/page-26-covid-19-vaccine.html.

3. Public Health Agency of Canada. Vaccine Confidence InfoBulletin. September 2022. Available from: https://canvax.ca/sites/default/files/PHAC%20Vaccine%20Confidence%20InfoBulletin_Volume%202%20Issue%209%20-%20September%202022.pdf.

4. World Health Organization. Interim statement on hybrid immunity and increasing population seroprevalence rates. Jun 1 2022. Available from: https://www.who.int/news/item/01-06-2022-interim-statement-on-hybrid-immunity-and-increasing-population-seroprevalence-rates.

5. Moore SC, Kronsteiner B, Longet S, Adele S, Deeks AS et al. Evolution of long-term hybrid immunity in healthcare workers after different COVID-19 vaccination regimens: a longitudinal observational cohort study. medRxiv. 2022:1-49.

6. Stamatatos L, Czarostki J, Wan Y-H, Homad LJ, Rubin V et al. mRNA vaccination boosts cross-variant neutralizing antibodies elicited by SARS-CoV-2 infection. Science. 2021;372(6549):1413-8.

7. Emerging Science Group of the Public Health Agency of Canada. Is there protective immunity after an Omicron infection? Canada Communicable Disease Report (CCDR). 48(November/December 2022). Available from: https://www.canada.ca/en/public-health/services/reports-publications/canada-communicable-disease-report-ccdr/monthly-issue/2022-48/issue-11-12-november-december-2022/protective-immunity-after-omicron-infection.html.

8. Public Health Agency of Canada. National Advisory Committee on Immunization (NACI) Statement: Guidance on an additional COVID-19 booster dose in the spring of 2023 for individuals at high risk of severe illness due to COVID-19. 2023 Mar 3. Available from: https://www.canada.ca/content/dam/phac-aspc/documents/services/publications/vaccines-immunization/national-advisory-committee-immunization-guidance-additional-covid-19-booster-dose-spring-2023-individuals-high-risk-severe-illness-due-covid-19/statement.pdf.

9. Bobrovitz N, Ware H, Ma X, Li Z, Hosseini R, Cao C, et al. Protective effectiveness of previous SARS-CoV-2 infection and hybrid immunity against the omicron variant and severe disease: a systematic review and meta-regression. The Lancet Infectious Diseases. 2023.

10. Institut National de Santé Publique du Quebec. Administration of COVID-19 booster doses: Recommendations for winter and spring 2023. Available from: https://www.inspq.qc.ca/en/publications/3284-covid-19-booster-doses-winter-spring-2023.

11. Public Health Agency of Canada. Canadian Immunization Guide [Internet]. Evergreen ed. Part 4 - Immunizing Agents: COVID-19 Vaccines. 2024. Available from:

https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-4-active-vaccines/page-26-covid-19-vaccine.html

12. Chen H, Huang Z, Chang S, Hu M, Lu Q, Zhang Y, Wang H, Xiao Y, Ge Y, Zou Y, Cui F. Immunogenicity and safety of an inactivated SARS-CoV-2 vaccine (Sinopharm BBIBP-CorV) co-administered with quadrivalent split-virion inactivated influenza vaccine and 23-valent pneumococcal polysaccharide vaccine in China: A multicentre, non-inferiority, open-label, randomised, controlled, phase 4 trial. Vaccine. 2022;40(36):5322-32.

13. Izikson R, Brune D, Bolduc JS, Bourron P, Fournier M, Moore TM, Pandey A, Perez L, Sater N, Shrestha A, Wague S. Safety and immunogenicity of a high-dose quadrivalent influenza vaccine administered concomitantly with a third dose of the mRNA-1273 SARS-CoV-2 vaccine in adults aged ≥ 65 years: a phase 2, randomised, open-label study. The Lancet Respiratory Medicine. 2022;10(4):392-402.

14. Lazarus R, Baos S, Cappel-Porter H, Carson-Stevens A, Clout M, Culliford L, Emmett SR, Garstang J, Gbadamoshi L, Hallis B, Harris RA. Safety and immunogenicity of concomitant administration of COVID-19 vaccines (ChAdOx1 or BNT162b2) with seasonal influenza vaccines in adults in the UK (ComFluCOV): a multicentre, randomised, controlled, phase 4 trial. The Lancet. 2021;398(10318):2277-87.

15. Toback S, Galiza E, Cosgrove C, Galloway J, Goodman AL, Swift PA, Rajaram S, Graves-Jones A, Edelman J, Burns F, Minassian AM. Safety, immunogenicity, and efficacy of a COVID-19 vaccine (NVX-CoV2373) co-administered with seasonal influenza vaccines: an exploratory substudy of a randomised, observer-blinded, placebo-controlled, phase 3 trial. The Lancet Respiratory Medicine 2022;10(2):167-79.

16. Janssen C, Mosnier A, Gavazzi G, Combadière B, Crepey P, Gaillat J, Launay O, Botelho-Nevers E. Co-administration of seasonal influenza and COVID-19 vaccines: A systematic review of clinical studies. . Human Vaccines & Immunotherapeutics. 2022;2131166.

17. Shenyu W, Xiaoqian D, Bo C, Xuan D, Zeng W, Hangjie Z, Qianhui Z, Zhenzhen L, Chuanfu Y, Juan Y, Gang Z. Immunogenicity and safety of a SARS-CoV-2 inactivated vaccine (CoronaVac) co-administered with an inactivated quadrivalent influenza vaccine: A randomized, open-label, controlled study in healthy adults aged 18 to 59 years in China. Vaccine. 2022;40(36):5356-65.

18. Domnich A, Orsi A, Trombetta CS, Guarona G, Panatto D, Icardi G. COVID-19 and Seasonal Influenza Vaccination: Cross-Protection, Co-Administration, Combination Vaccines, and Hesitancy. Pharmaceuticals. 2022;15(3):322.

19. Bentov Y, Beharier O, Moav-Zafrir A, et al. Ovarian follicular function is not altered by sars-cov-2 infection or bnt162b2 mrna covid-19 vaccination. Hum Reprod. 2021;36(18):2506-13.

20. Wang M, Yang Q, Ren X, et al. Investigating the impact of asymptomatic or mild sarscov-2 infection on female fertility and in vitro fertilization outcomes: A retrospective cohort study. EClinicalMedicine. 2021;38:101013.

21. Society of Obstetricians and Gynecologists of Canada. Statement on COVID-19 vaccination and fertility. 2021. Available from: https://sogc.org/common/Uploaded%20files/Latest%20News/EN_SOGCStatement_COVID-19Vaccination-Fertility.pdf

22. BC Centre for Disease Control. BC Communicable Disease Control Manual, Chapter 2: Immunization, Part 1 - Immunization Schedules, pg 3. 2020. Available from: http://www.bccdc.ca/resource-gallery/Documents/Guidelines%20and%20Forms/Guidelines%20and%20Manuals/Epid/CD%20Manual/Chapter%202%20-%20Imms/Part_1_Schedules.pdf.

23. Villar J, Conti CP, Gunier RB, Ariff S, Craik R, Cavoretto PI, Rauch S, Gandino S, Nieto R, Winsey A, Menis C, et al. Pregnancy outcomes and vaccine effectiveness during the period of omicron as the variant of concern, INTERCOVID-2022: a multinational, observational study. Lancet. Feb 2023;401:447-57.

24. Allotey J, Fernandez S, Bonet M, Stallings E, Yap M, Kew T, et al. Clinical manifestations, risk factors, and maternal and perinatal outcomes of coronavirus disease 2019 in pregnancy: living systematic review and meta-analysis. bmj. 2020;370.

25. Havers FP. COVID-19-Associated Hospitalizations Among Children and Adults - COVID-NET. RESP-NET Hospitalization Surveillance Team: ACIP; 2024. Available from: https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2024-06-26-28/02-COVID-Havers-508.pdf.

26. Prabhu M, Riley L. Coronavirus disease 2019 (COVID-19) vaccination in pregnancy. Obstetrics & Gynecology. Mar 2023;141(3):473-82.

27. Shimabukuro TT, Kim SY, Myers TR, Moro PL, Oduyebo T, Panagiotakopoulos L, Marquez PL, Olson CK, Liu R, Chang KT, Ellington SR, Burkel VK, Smoots AN, Green CJ, Licata C, Zhang BC, Alimchandani M, Mba-Jonas A, Martin SW, Gee JM, Meaney-Delman DM. CDC v-safe COVID-19 Pregnancy Registry Team. Preliminary Findings of mRNA Covid-19 Vaccine Safety in Pregnant Persons. N Engl J Med. 2021;384:2273-82.

28. Castillo E and Poliquin V. Immunization in pregnancy. J Obstet Gynaecol Can [Internet]. 2018;40(4):478-89.

29. National Advisory Committee on Immunization (NACI). Guidance on the use of COVID-19 vaccines in the fall of 2023. July 2023. Available from: https://www.canada.ca/en/public-health/services/publications/vaccines-immunization/national-advisory-committee-immunization-guidance-use-covid-19-vaccines-fall-2023.html.

30. National Advisory Committee on Immunization (NACI). Updated guidance on COVID-19 vaccination timing for individuals previously infected with SARS-CoV-2. February 2022. Available from: https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/rapid-response-guidance-covid-19-vaccination-timing-individuals-previously-infected-sars-cov-2.html.

31. Immunization Action Coalition. Ask the Experts: COVID-19. 12 September 2023. Available from: https://www.immunize.org/askexperts/experts_cov.asp.

32. Saleh E, Moody MA, Walter EB. Effect of antipyretic analgesics on immune responses to vaccination. Hum Vaccin Immunother [Internet]. 2016.;12(9):2391-402.

33. Chau-Giendinning H, Baber B, Neher JO, Safranek S. Do prophylactic antipyretics reduce vaccination-associated symptoms in children? J Fam Pract [Internet]. 2021;69(3):E21-2.

34. Das RR, Panigrahi I, Naik SS. The effect of prophylactic antipyretic administration on post-vaccination adverse reactions and antibody response in children: a systematic review. PLoS One [Internet]. 2021;69(3):e106629.

35. BC Cancer. COVID-19 and Cancer Screening. Does the COVID-19 vaccine affect my screening mammogram? 2021

36. Public Health Agency of Canada. Canadian Immunization Guide [Internet]. Evergreen ed. Part 1 - Key Immunization Information: Vaccine Administration Practices. 2017. Available from: https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-1-key-immunization-information/page-8-vaccine-administration-practices.html.

37. CDC. Epidemiology and Prevention of Vaccine-Preventable Diseases. The Pink Book Course Textbook 14th edition. Chapter 6: Vaccine Administration. Available from:

https://www.cdc.gov/pinkbook/hcp/table-of-contents/chapter-6-vaccine-administration.html

38. Clinical Skills [Internet]. Maryland Heights (MO): Elsevier Inc. Skills: Medication Administration: Intramuscular Injection 2021. Available from: https://point-of-care.elsevierperformancemanager.com/skills/376/quick-sheet?skillId=GN_21_5.

39. Moshe Ipp, Anna Taddio, Jonathan Sam, Morton Goldbach, and Patricia C Parkin. Vaccine‐related pain: randomised controlled trial of two injection techniques. 2007.

Both the Pfizer-BioNTech Comirnaty® and Moderna Spikevax® COVID-19 vaccines are mRNA vaccines. Messenger RNA (mRNA) is the ‘blueprint’ that cells use to synthesize proteins required for our physiology. The COVID-19 mRNA vaccines use mRNA contained inside a lipid nanoparticle (LNP) that contains the synthetic nucleotide sequences that codes for the SARS-CoV-2 spike protein. After injection, the LNP is taken up by immune system cells, and once inside a cell, the mRNA provides the instructions that allow the cell to manufacture the spike protein. Once manufactured, the spike protein exits the cell, and becomes anchored onto the cell's surface. The immune system is activated to recognize the spike protein as foreign and initiates an immune response. The mRNA is then cleared by the cell’s natural mRNA degradation process. The estimated half-life for mRNA after injection is about 8-10 hours before degradation by native RNases (enzymes that break up the mRNA) in the body; the expressed spike protein persists in the body for several days and during this time continues to stimulate the immune response. mRNA vaccines are not live vaccines and cannot cause infection in the host. The delivered mRNA does not replicate, and does not enter the cell nucleus or interact with or alter the recipient’s DNA.^{1- 3}

Several mRNA vaccines are under development for other infections including cytomegalovirus, human metapneumovirus, parainfluenza virus type 3, Zika and influenza viruses.

Manufacturing of mRNA vaccines has been under development for a decade. The process is cell-free (does not use human or other animal cells) and does not use vectors (like other viruses) or animal products, preservatives or adjuvants.

History of anaphylactic reaction to any component of the vaccine is generally considered a contraindication. Anaphylaxis has been reported to be very rare following mRNA vaccination. However, based on recent studies demonstrating that individuals who experienced anaphylaxis following their first dose of mRNA vaccine were able to receive their second dose of mRNA vaccine with either mild or no side effects, re-vaccination may be offered with the same vaccine or the same platform if a risk assessment deems that the benefits outweigh the potential risks for the individual, informed consent is provided, and the following criteria are met:^4-6

• consultation with an allergist or another appropriate physician before receiving future doses of a COVID-19 mRNA vaccine
• a controlled setting where the vaccine can be administered with expertise and equipment to manage anaphylaxis
• an observation period of at least 30 minutes after vaccination (the normal observation period for people who have not experienced a severe immediate allergic reaction after vaccination is 15 minutes)

Alternatively, such individuals may be offered the Novavax COVID-19 vaccine if they are age-eligible and vaccine is available.

Both Pfizer and Moderna COVID-19 mRNA vaccines contain polyethylene glycol (PEG) which can be found in various products such as: bowel preparation products for colonoscopy, laxatives, cough syrup, cosmetics, contact lens care solutions, skin care products and as an additive in some food and drinks. No cases of anaphylaxis to PEG in foods and drinks have been reported.‎

‎Tromethamine (Tris or trometamol) is used as a buffer in vaccines and medications, including those for use in children, to improve stability and prevent pH fluctuations in the solution. Tromethamine is widely used in several medications for topical, enteral or parenteral administration. It is also used in cosmetics as an emulsifier.⁷ No safety concerns have been identified with tromethamine. While tromethamine has been identified as a potential allergen, a review of existing evidence did not identify any cases of allergic reactions to tromethamine in children.⁸

Tromethamine has been identified as a potentially allergenic excipient and is present in the Pfizer-BioNTech and Moderna COVID-19 vaccines. However, there is increasing evidence that this is not the culprit excipient and/or the reactions are not IgE-mediated. This remains under investigation.⁶

In situations of suspected hypersensitivity or non-anaphylactic allergy to COVID-19 vaccine components, the vaccine should be administered in a controlled setting with expertise and equipment to manage anaphylaxis, with an extended period of observation post-vaccination of at least 30 minutes.

For more information, refer to the BC Immunization Manual, Part 3: Management of Anaphylaxis in a Non-Hospital Setting, Supervision of Vaccines Post-immunization.

The mRNA vaccines do not contain a preservative to prevent microbial contamination following first vial puncture or dilution and therefore they must be used within the specified time periods indicated within the respective product pages in the BC Immunization Manual, Part 4 – Biological Products, COVID-19 Vaccines.

For more information with regard to receiving and handling the Pfizer-BioNTech and Moderna vaccines, refer to the BC Immunization Manual, Appendix E: Management of Biologicals, Guidance for Receiving and Handling the Pfizer-BioNTech COVID-19 mRNA Vaccine (including dry ice procedures) and Guidance for Receiving and Handling the Moderna COVID-19 mRNA Vaccine. Additional information, including standard operating procedures can be found on the COVID-19 Immunize BC Operations Centre: Standard Operating Procedures page.

1. Public Health Agency of Canada. Recommendations on the use of COVID-19 vaccines. 2021 [Jan 12 2021]. Available from: https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/recommendations-use-covid-19-vaccines.html.

2. U.S. Food & Drug Administration [Internet]. Silver Spring (MD): U.S. Food & Drug Administration. 2020 meeting materials, vaccines and related biological products advisory committee December 10, 2020 meeting announcement. 2020 Available from: https://www.fda.gov/advisory-committees/advisory-committee-calendar/vaccines-and-related-biological-products-advisory-committee-december-10-2020-meeting-announcement.

3. U.S. Food & Drug Administration [Internet]. Silver Spring (MD): U.S. Food & Drug Administration. 2020 meeting materials, vaccines and related biological products advisory committee December 17, 2020 meeting announcement. 2020. Available from: https://www.fda.gov/advisory-committees/advisory-committee-calendar/vaccines-and-related-biological-products-advisory-committee-december-17-2020-meeting-announcement.

4. Public Health Agency of Canada. Canadian Immunization Guide [Internet]. Evergreen ed. Part 4 - Immunizing Agents: COVID-19 Vaccines. 2023. Available from: https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-4-active-vaccines/page-26-covid-19-vaccine.html

5. Public Health Agency of Canada. Canadian Immunization Guide [Internet]. Evergreen ed. Part 2 - Vaccine Safety: Anaphylaxis and other acute reactions following vaccination. 2023. Available from:

https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-2-vaccine-safety/page-4-early-vaccine-reactions-including-anaphylaxis.html

6. Nilsson L, Csuth Á, Storsaeter J, Garvey LH, Jenmalm MC. Vaccine allergy: evidence to consider for COVID-19 vaccines. 2021;214:401,9.

7. Canadian Society of Allery and Clinical Immunology. COVID-19 Vaccine Testing & Administration Guidance for Allergists/Immunologists from the CSACI. 2021. Available from: https://csaci.ca/wp-content/uploads/2021/11/2021-11-15-REVISED-UPDATE-COVID-19-Vaccine-Testing-Administration-Guidance_LBL.pdf

8. Public Health Agency of Canada. Statement from the Council of Chief Medical Officers of Health (CCMOH): COVID-19 Vaccination in Children 5-11 years of age. 2021. Available from: https://www.canada.ca/en/public-health/news/2021/11/statement-from-the-council-of-chief-medical-officers-of-health-ccmoh-covid-19-vaccination-in-children-5-11-years-of-age.html.

The Novavax COVID-19 vaccine is a recombinant protein subunit vaccine. While this type of vaccine technology has been used for other vaccines such as the hepatitis B vaccine, this is the first COVID-19 vaccine authorized in Canada which uses this technology.

Protein subunit vaccines are created by inserting a small piece of the virus’s genetic code into another cell (Novavax uses the Spodoptera frugiperda insect cell line) which instructs the cell to start building the SARS-CoV-2 spike protein. The virus spike protein is then extracted from the cell, purified and used as the active ingredient in the vaccine to stimulate an immune response. The Novavax COVID-19 vaccine includes a new type of adjuvant, Matrix-M, which helps the vaccine produce a better immune response.

Although the Novavax vaccine targeting the Omicron JN.1 variant is approved for use by Health Canada, it is not currently available as part of BC's fall immunization campaign. All available avenues to secure a supply of the updated vaccine for the fall are being explored. If product does become available in BC, more information can be found in the BC Immunization Manual.

If the Novavax COVID-19 vaccine is available, it may be offered to individuals 12 years of age and older as an alternative to COVID-19 mRNA vaccines. The Novavax COVID-19 vaccine is interchangeable with COVID-19 mRNA vaccines. Furthermore, the previous preferential recommendation is no longer in place as the most recently updated mRNA and protein subunit COVID-19 vaccines target the same sublineage, and evidence continues to support the effectiveness and safety profile of the protein subunit vaccine platform.^{1, 2}

Novavax COVID-19 vaccine is contraindicated for individuals with a history of anaphylactic reaction to a previous dose of the vaccine or to any component of the vaccine. These individuals should be offered an mRNA COVID-19 vaccine and observed for at least 30 minutes after immunization.

The Novavax COVID-19 vaccine contains polysorbate 80 which is considered a potential allergen. Polysorbate 80 can be found in various products such as cosmetics and medical preparations including vitamin oils, tablets, and anticancer agents.

For a complete list of components in the vaccine see the Novavax Nuvaxovid^® Product Monograph.

1. National Advisory Committee on Immunization (NACI). Guidance on the use of COVID-19 vaccines during the fall of 2024. 2024 [cited 2024 Jul 8]. Available from: https://www.canada.ca/en/public-health/services/publications/vaccines-immunization/national-advisory-committee-immunization-guidance-covid-19-vaccines-fall-2024.html

2. National Advisory Committee on Immunization (NACI). Updated guidance on the use of protein subunit COVID-19 vaccine (Novavax Nuvaxovid). 2024. Available from: 

https://www.canada.ca/en/public-health/services/publications/vaccines-immunization/national-advisory-committee-immunization-updated-guidance-use-protein-subunit-covid-19-vaccine-novavax-nuvaxovid.html

To date, people with moderately to severely compromised immune systems have been observed to generally have lower antibody responses and lower vaccine effectiveness compared to immunocompetent individuals, although this varies depending on the underlying condition or immunosuppressive therapy.

NACI continues to recommend an additional dose of COVID-19 vaccine in the primary series for those who are moderately to severely immunocompromised to help improve the immune response and vaccine effectiveness.¹

Unvaccinated individuals 5 years of age and older who are moderately to severely immunocompromised should receive 2 doses of COVID-19 vaccine, compared to the 1-dose schedule recommended for those in this age group who are not immunocompromised. In addition, previously unvaccinated individuals who are moderately to severely immunosuppressed with a self-declared recommendation by their health care provider are eligible to receive a 3-dose series. Although 2 doses can provide good protection, not all individuals with immuncompromising conditions would respond the same way to vaccination. Furthermore, not all individuals who are moderately to severely immunosuppressed have prior SARS-CoV-2 infection and they are lacking the additional protection offered by hybrid immunity. Hence, in some cases, a third dose would be needed to develop adequate protection.² 

New HSCT and CART therapy recipients initiating their series are considered immunologically naive and should receive a 3-dose series regardless of the COVID-19 vaccine formulation. This is consistent with the premise that 3 antigen exposures are helpful to establish a foundation of robust immunity.²

For those 6 months to 4 years of age who are moderately to severely immunocompromised NACI continues to recommend either 3 doses of Moderna COVID-19 vaccine (preferred due to fewer doses required) or 4 doses of Pfizer COVID-19 vaccine. However, note that for individuals between the age of 6 months to 11 years (inclusive), Moderna KP.2 COVID-19 vaccine is the only product currently available in BC. The additional doses are needed in this very young population as they are less likely to have been infected, and therefore less likely to have developed hybrid immunity, compared to individuals 5 years of age and older.²

‎HSCT generally involves the ablation of the bone marrow followed by re-implantation of the person’s own stem cells (autologous HSCT) or stem cells from a donor (allogeneic HSCT). HSCT recipients should be viewed as "never immunized" and require re-immunization after transplant because the ablation of hematopoietic cells in the bone marrow pre-transplant eliminates most or all immune memory.³ Similarly, CART therapy recipients should be considered "never immunized" as this therapy targets lymphocytes.

NACI continues to recommend COVID-19 re-immunization of HSCT and CART therapy recipients and the receipt of at least three doses of a COVID-19 vaccine. As a result of the prolonged period of immune suppression following transplantation, revaccination with inactivated vaccine is typically recommended 6-12 months post-transplant, however for certain vaccines such as influenza and COVID-19 vaccines, revaccination can occur as early as 3 months post-transplant. The HSCT specialist will determine the appropriate time to commence immunizations and will provide written guidance to the client for sharing with the immunizing health care provider.

For more information see:

• Clinical Guidance on COVID-19 Vaccines for people with hematological malignancy at any stage of treatment and/or who have undergone hematopoietic stem cell transplant or CAR-T cell therapy in the past 6 months 

1. Public Health Agency of Canada. Canadian Immunization Guide [Internet]. Evergreen ed. Part 4 - Immunizing Agents: COVID-19 Vaccines. 2023. Available from: https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-4-active-vaccines/page-26-covid-19-vaccine.html.

2. National Advisory Committee on Immunization (NACI). Guidance on the use of COVID-19 vaccines during the fall of 2024. 2024 [cited 2024 Jul 8]. Available from: https://www.canada.ca/content/dam/phac-aspc/documents/services/publications/vaccines-immunization/national-advisory-committee-immunization-guidance-covid-19-vaccines-fall-2024/naci-statement-2024-05-03.pdf

3. Public Health Agency of Canada. Canadian Immunization Guide. Part 3 - Vaccination of Specific Populations: Immunization of immunocompromised persons. 2022. Available from: https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-3-vaccination-specific-populations/page-8-immunization-immunocompromised-persons.html.

Very rare cases of severe immediate allergic reactions (e.g., anaphylaxis) have been reported following vaccination with mRNA COVID-19 vaccines. Most of the reported cases have occurred within 30 minutes of vaccination. Individuals tend to recover quickly with appropriate treatment and there have been no fatalities nor long-term morbidity observed with any of these severe immediate allergic reactions in Canada.

Studies have shown that individuals with a severe immediate allergic reaction after a previous dose of mRNA vaccine can be re-vaccinated with the same vaccine or another mRNA COVID-19 vaccine following an appropriate medical assessment and provided certain criteria are met – see the PRECAUTIONS section within the respective product pages within the BC Immunization Manual Part 4: Biological Products, COVID-19 Vaccines. In these studies, re-vaccination was safe and well tolerated with predominantly no, or mild, reactions after re-vaccination when provided in a controlled environment. Available evidence also suggests that most of the reported severe immediate allergic reactions following mRNA COVID-19 vaccines are likely not immunoglobulin E (IgE)-mediated and therefore have a low risk of recurrence following future vaccine doses.¹

Reports of reactions to COVID-19 vaccines have increased concerns about their safety for individuals with allergies. The Canadian Society of Allergy and Clinical Immunology (CSACI) guidelines stress that there is a low risk for allergic reactions to vaccines, and non-allergic reactions to vaccines are more common than allergic reactions. In addition, non-allergic reactions to vaccines also include anxiety-related adverse events that can mimic allergic reactions.² It is important to note that other, less serious reactions may mimic allergic reactions such as vasovagal syncope which are not contraindications to further vaccination.³

Additional information regarding allergies and COVID-19 vaccine for the public can be found in the CSACI’s COVID-19 Vaccines FAQ resource.

For more information review the contraindications and precautions sections in the COVID-19 vaccine product pages of the BC Immunization Manual Part 4: Biological Products, COVID-19 Vaccines.

To learn more about anaphylaxis refer to the BC Immunization Manual Part 5: Adverse Events Following Immunization.

It is important to first determine whether the reaction was an anaphylactic reaction. If an individual experienced a serious adverse event following immunization (AEFI), an AEFI report may be available in the provincial immunization data system. The AEFI report will contain details about the AEFI as well as the Medical Health Officer (MHO) recommendation on further immunization.

Although anaphylaxis occurs rarely after vaccination, it is potentially life threatening and requires immediate treatment. It is characterized by sudden onset, rapid progression of signs and symptoms and is set apart from simple allergic reactions by the simultaneous involvement of several organ systems. Anaphylaxis that has been proven to be causally associated with vaccines is estimated at a frequency of 1.3 episodes per 1,000,000 doses of vaccines administered.⁴

For individuals with a history of anaphylactic reaction to a previous dose of a COVID19 mRNA vaccine, re-vaccination (i.e., administration of a subsequent dose in the series when indicated) may be offered with an mRNA vaccine if a risk assessment deems that the benefits outweigh the potential risks for the individual and if informed consent is provided. Prior to re-vaccination, consultation with an allergist or another appropriate physician (e.g., Medical Health Officer) is advised. If re-vaccinated, vaccine administration should be done in a controlled setting with expertise and equipment to manage anaphylaxis, with an extended period of observation of at least 30 minutes after revaccination.

History of anaphylactic reaction to a previous dose of Novavax COVID-19 vaccine or to any component of the vaccine is considered a contraindication to receipt of this vaccine. These individuals should be offered a COVID-19 mRNA vaccine and observed for at least 30 minutes after immunization.

The checklist below can be used as a tool to assist health care providers to determine how to proceed when an individual reports an allergic reaction following a COVID-19 vaccine.

• Was the event considered a severe allergic reaction or physician-diagnosed anaphylaxis?
• Is there a history of anaphylactic reaction to any component of COVID-19 vaccine?
• Was the event reported to public health as an AEFI?
• If reported to public health, is an MHO recommendation available?
• Did the MHO recommendation indicate that a COVID-19 vaccine from a different vaccine platform be provided?

Phase 2/3 of clinical trial data evaluated the frequency of adverse events in children aged 5-11 years for the pediatric Pfizer-BioNTech vaccine (10 mcg) and children 6-11 years for the Moderna vaccine (50 mcg). Local reactions including pain, redness and swelling were very common, appearing 1-2 days after any dose and typically resolved within 1-3 days. Systemic events were mild or moderate in severity and included fatigue, headache, muscle pain, chills, fever and joint pain. Onset of systemic events was within 1-4 days after vaccine receipt with a median duration of 1 day.‎ Available post-market vaccine safety data from V-safe, Vaccine Safety Datalink (VSD) and Vaccine Adverse Event Reporting System (VAERS) in the US as of September 2022 show that the Moderna Spikevax (25 mcg) and Pfizer-BioNTech Comirnaty (3 mcg) COVID-19 mRNA vaccines are well tolerated among children aged 6 months to 5 years. No safety signals (including myocarditis) have been identified after administration of about 1.5 million vaccine doses.⁵ The most frequent reactions reported for children aged 6 months to 2 years included irritability or crying, sleepiness, and loss of appetite. These reactions are common after childhood vaccination.⁵

‎Myocarditis is an inflammation of the heart muscle; if it is accompanied by pericarditis, an inflammation of the thin tissue surrounding the heart (the pericardium), it is referred to as myopericarditis. Symptoms can include shortness of breath, chest pain, or the feeling of a rapid or abnormal heart rhythm. Symptoms can be accompanied by abnormal tests (e.g., electrocardiogram, serum troponins, echocardiogram). These are inflammatory disorders of the outer lining of the heart and heart muscle, and occur for a variety of reasons including in association with viral infections.

As such, myocarditis can occur as a complication of COVID-19 infection. In Israel, COVID-19 infection has been estimated to cause myocarditis at a rate of 11 events per 100,000 persons among individuals aged 16 years and older. A retrospective study from the US found myocarditis (or pericarditis or myopericarditis) rates after primary COVID-19 infection to be as high as 45 cases per 100,000 patients in young males aged 12-17 years.

mRNA COVID-19 Vaccines:

Myocarditis following mRNA COVID-19 vaccination tends to have a similar epidemiologic profile to classic myocarditis (unrelated to COVID-19), as it occurs more commonly in adolescents and young adult males. Classic myocarditis is less common in younger children.⁶

Cases of myocarditis/pericarditis following COVID-19 mRNA vaccination occur most commonly in adolescents and young adults (12 to 29 years of age) however, the risk is considered rare. It is important to note, as well, that teens and adults are at higher risk of developing myocarditis/pericarditis following COVID-19 infection compared to COVID-19 mRNA vaccination; as such, the risk of experiencing myocarditis is greater in an unvaccinated person than a vaccinated person.⁷

When cases of myocarditis and/or pericarditis following vaccination with COVID-19 mRNA vaccines were first detected, NACI recommended Pfizer BioNTech Comirnaty as the preferred product over Moderna Spikevax for the primary series in individuals 12-29 years due to the higher risk of myocarditis and/or pericarditis observed following the Moderna Spikevax 100 mcg original monovalent vaccine primary series (especially after the second dose). However this product preference is no longer being recommended. Compared to the original monovalent primary series, the risk of myocarditis and/or pericarditis is now expected to be lower due to the use of a 1-dose schedule in most individuals and potentially due to a lower dosage of the available Moderna Spikevax vaccine (50 mcg in the XBB.1.5 formulation compared to 100 mcg in the original monovalent formulation).⁸

Myocarditis/pericarditis usually occurs within a week of vaccination and is more common:

• After the second dose
• In males than females
• After receipt of the Moderna vaccine than the Pfizer-BioNTech vaccine

In both Canada and the US, no deaths attributed to COVID-19 mRNA vaccine-related myocarditis have been identified in adolescents or young adults.

Available data indicate that most individuals affected have responded well to conservative therapy and have recovered quickly.³

Protein Subunit Vaccine:

Pericarditis and myocarditis in association with Novavax COVID-19 vaccine have been reported internationally and in Canada per Public Health Agency of Canada. A longer interval of 8 weeks between doses in the primary series may reduce the likelihood of pericarditis and myocarditis. Most cases recover fully. The exact cause of these events is not known but is thought to be related to the immune response to the spike protein which is also important in immunity against COVID-19 virus.

Current recommendation:

Additional doses of a COVID-19 vaccine should be deferred in those who experienced a physician-diagnosed myocarditis or pericarditis event following a previous dose of a COVID-19 vaccine. However, those with a history compatible with pericarditis who had no cardiac workup or had normal investigations may proceed to further vaccination once symptoms have resolved and 90 days have passed since receipt of the dose associated with the event.⁹ For those with confirmed myocarditis (with or without pericarditis), an individual risk/benefit discussion between the patient and their healthcare provider should occur so that the patient (with their parent/guardian as applicable) can make an informed decision about proceeding with a subsequent dose. If another dose is offered, the Pfizer-BioNTech COVID19 vaccine should be offered because of the lower rate of myocarditis/pericarditis compared to the Moderna vaccine.

Deferral is not required for those with a prior history of myocarditis or pericarditis that is unrelated to COVID-19 vaccines and are no longer being followed by a medical professional for heart issues.

Informed consent should emphasize the unknown risk of recurrence of myocarditis and/or pericarditis for these individuals and the importance of seeking immediate medical assessment and care should these symptoms develop.

In BC, we have ensured that health care providers are aware of this observation and the possibility of it being causally linked to the vaccine, and how to diagnose and report this event when it occurs after a COVID-19 vaccine.

COVID-19 vaccine would only be contraindicated if the component to which the individual is allergic is also present in the influenza vaccine. Influenza vaccine and COVID-19 vaccine ingredients vary depending on the specific product. Refer to the respective product monographs for each vaccine or go to the BC Immunization Manual, Part 4 – Biological Products, COVID-19 and influenza vaccine pages for ingredient lists.

With the exceptions of FluLaval® Tetra and Fluad®, which both contain polysorbate 80, none of the other influenza vaccines contain the potential allergens that are in the mRNA vaccines (polyethylene glycol [PEG]) or protein subunit vaccine (polysorbate 80). In addition, the COVID-19 vaccines do not contain any of the potential allergens found in the influenza vaccines (e.g., ovalbumin/egg protein, thimerosal, gelatin, antibiotics). These vaccines may have some other components in common but these are not known to be allergens, i.e., sucrose and various salts.‎

‎Yes. With GBS, typically the biological basis would have been an immune mediated reaction to the antigens in the vaccine. As these antigens are not shared across influenza and COVID-19 vaccines, GBS following receipt of an influenza vaccine is not a contraindication to receiving a COVID-19 vaccine.

Any health professional who is aware of an adverse event following immunization must report the event to the medical health officer as per the Public Health Act. Information on AEFI reporting can be found on the BCCDC COVID-19 Vaccination Health Care Provider Toolkit on the Adverse Events Following Immunization (AEFIs) page. More information about reporting anaphylaxis and other allergic reactions can be found in the BC Immunization Manual Part 5 - Adverse Events Following Immunization. In addition, the Report of Adverse Event Following Immunization is a shortened two page form available for non-public health professionals reporting AEFI.

1. Public Health Agency of Canada. Canadian Immunization Guide [Internet]. Evergreen ed. Part 4 - Immunizing Agents: COVID-19 Vaccines. 2023. Available from: https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-4-active-vaccines/page-26-covid-19-vaccine.

2. Vander Leek, T.K., Chan, E.S., Connors, L. et al. COVID-19 vaccine testing & administration guidance for allergists/immunologists from the Canadian Society of Allergy and Clinical Immunology (CSACI). Allergy Asthma Clin Immunol. 2021;17(29).

3. Public Health Agency of Canada. Recommendations on the use of COVID-19 vaccines. 2021 [Jan 12 2021]. Available from: https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/recommendations-use-covid-19-vaccines.html.

4. Public Health Agency of Canada. Canadian Immunization Guide [Internet]. Evergreen ed. Part 2 - Vaccine Safety: Anaphylaxis and other acute reactions following vaccination. 2020. Available from: https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-2-vaccine-safety/page-4-early-vaccine-reactions-including-anaphylaxis.

5. Public Health Agency of Canada. Canadian Immunization Guide [Internet]. Evergreen ed. Part 4 - Immunizing Agents: COVID-19 Vaccines. 2024. Available from:

https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-4-active-vaccines/page-26-covid-19-vaccine.html

6. National Advisory Committee on Immunization (NACI). Recommendation on the use of the Pfizer-BioNTech COVID-19 vaccine (10 mcg) in children 5-11 years of age. November 2021. Available from: https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/recommendations-use-covid-19-vaccines/pfizer-biontech-10-mcg-children-5-11-years-age.html.

7. Children’s Hospital of Philadelphia. Feature Article: 3 Considerations for COVID-19 Vaccination of 5-11 year old Children. November 2021. Available from: 

https://www.chop.edu/sites/default/files/parents-pack-newsletter-nov2021.pdf.

8. National Advisory Committee on Immunization (NACI). Updated guidance on the use of COVID-19 vaccines in individuals who have not previously been vaccinated against COVID-19. 2023 Oct 27. Available from: https://www.canada.ca/content/dam/phac-aspc/documents/services/publications/vaccines-immunization/national-advisory-committee-immunization-updated-guidance-covid-19-vaccines-individuals-not-previously-vaccinated/naci-statement-2023-10-27.pdf.

9. National Advisory Committee on Immunization (NACI). Summary of NACI advice on vaccination with COVID-19 vaccines following myocarditis (with or without pericarditis). 2022 Jan 14. Available from: https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/summary-advice-vaccination-covid-19-vaccines-following-myocarditis-with-without-pericarditis.html.