This evidence review was compiled by members of the CITF Secretariat with the input from experts affiliated with the CITF and does not necessarily reflect the views of all CITF members.


Dr. Jim Kellner, CITF Leadership Group member & CITF Pediatric Network lead
Dr. Scott Halperin, CITF Leadership Group member and CITF Vaccine Surveillance Working Group Co-Chair
Dr. Caroline Quach, CITF Leadership Group member and CITF Vaccine Surveillance Working Group Co-Chair
Dr. Manish Sadarangani, CITF Pediatric Network member
Dr. Karina Top, CITF Vaccine Surveillance Working Group member
Dr. Bruce Mazer, Associate Scientific Director, Strategy, CITF Secretariat
Dr. Tim Evans, CITF Executive Director
The CITF Secretariat

As a safe and effective COVID-19 vaccine is now available for school-aged children, it is important to reflect on the multiple streams of benefits arising from their rapid roll-out. Successful immunization campaigns protect children from severe disease, help lower community transmission of the virus, allow the re-establishment of social networks, support the continuance of in-class schooling, and permit the full resumption of extra-curricular activities. Not only can pediatric vaccines protect children’s health, but they can also hasten the return to normal we have all been waiting for.

The appearance of COVID-19-induced MIS-C in children

Early in the pandemic, the original strain of SARS-CoV-2, sometimes called the ancestral strain, rarely resulted in severe outcomes in children (Lee, 2020). This began to change in April 2020, when clusters of cases of multisystem inflammatory syndrome in children (MIS-C) appeared and were subsequently linked to SARS-CoV-2 infection (Feldstein, 2020). Although rare, MIS-C is a condition that is characterized by severe and often life-threatening inflammation of multiple organ systems, including the heart. Accumulating evidence has shown that the onset of MIS-C is four to eight weeks after the initial COVID-19 diagnosis and is distinct from acute COVID-19-related hyperinflammation seen in adults (Vella, 2021; Feldstein, 2020).

The impact of the Delta variant

More recently, the virus has evolved, resulting in more young children catching the virus. While earlier variants of concern (VOCs) such as Alpha and Beta did not lead to a lot of hospital admissions and severe disease in children, the rise of the highly transmissible Delta variant, coupled with the loosening of public health restrictions and the vaccination of older children and adults, appears to have changed the narrative. As seen in the United States, the Delta variant surge led to an increased number of children getting infected, and by virtue, an increased number of pediatric hospitalizations due to COVID-19 (Eyre, 2021; Valentine 2021). Moreover, Chief Public Health Officer of Canada Dr. Theresa Tam noted at a press conference on November 5, 2021, that those under 12 years old represented over 20% of daily cases at the time, despite only representing 12% of the country’s population (CTV News). Given the lack of understanding of potential long-term impacts of COVID-19 in children, it is important to utilize an array of public health interventions to help protect children in this evolving pandemic. As we have seen in adult populations, effective vaccination can play a key role in protecting children from infection with SARS-CoV-2.

COVID-19 can have serious effects on children

Although the number of severe infections in young people is much lower than in adults, there have been over 900 deaths due to COVID-19 in the 0-18 age range in the United States (CDC) and 19 deaths in the 0-19 age range in Canada (Government of Canada). Canada has also seen nearly 2,000 children and adolescents (aged 0 to 19) hospitalized with COVID-19, including approximately 270 for MIS-C since the beginning of the pandemic (Laverty, 2021). As new variants emerge, protection by vaccination will help decrease these severe infection-related outcomes.

In addition to directly protecting children against COVID-19, vaccination will promote their safe and healthy development. Studies in Canada conducted by research teams supported by the COVID-19 Immunity Task Force (CITF) have shown an increase in adverse mental health indicators, including anxiety and depression, among children (Li 2021; Cost 2021; CHILD Study). School, and the socialization that goes along with it, are vital to healthy child development (Li 2020). Immunization of school-aged children will ensure that the education system remains intact with children attending classes and extracurricular activities in-person and experiencing the benefits of community interaction. Importantly, having children in regular school environments assures that their social, educational, and developmental needs are adequately addressed. Furthermore, it allows parents to return to work without the concern of potential school closures.  Much to the frustration of children, parents, and educators, in the absence of widescale immunization, and public health measures such as rapid testing, any COVID-19-like symptoms may require testing and self-isolation, while a COVID-19 case in a classroom may lead to additional monitoring or self-isolation among peers at school and potential school shutdowns.

Vaccines can help reduce virus transmission

Encouragingly, Pfizer-BioNTech’s Comirnaty COVID-19 vaccination regimen consisting of two 10-μg doses (one third of the adolescent/adult dose) was shown to be 90.7% efficacious against COVID-10 in a phase 3 trial of children 5 to 11 years of age that took place in the Delta variant era (Walter, 2021). Bringing further comfort to families, an indirect benefit of pediatric vaccination is that they will reduce onward transmission to household members, which is especially important for family members who are immunocompromised and/or elderly (and thus unable to strongly respond to the vaccine) or are still too young to be vaccinated. While fully vaccinated people may still acquire and transmit the virus, research so far has shown that they may be contagious for a shorter period of time than unvaccinated individuals and they are less likely to transmit the virus, so widespread vaccination can offer community-wide protection (Chia 2021; Singanayagam, 2021; Eyre, 2021). This means that family and social networks consisting of extended family, neighbours, and other loved ones, can be stitched back together without fear of infecting one another.

Vaccines are scrutinized rigorously for safety before being approved in Canada

Clinical and safety data submitted by vaccine manufacturers to federal regulatory approval bodies is scrutinized with utmost rigor before the products are deemed accepted and available for use. As of November 7, 2021 over 59 million doses had been administered in Canada alone, meaning 85% of all Canadians over the age of 12 were fully vaccinated by that date (Government of Canada). The United States approved the pediatric COVID-19 vaccine earlier than Canada and as of November 17, 2021 had already administered over 6.6 million doses (US CDC). Real-world data have shown COVID-19 vaccines to be both safe and effective in populations ranging from the young to older frail people (Skowronski, 2021; Sadarangani, 2021). COVID-19 vaccines have significantly reduced severe outcomes and death caused by COVID-19, allowing us to begin to return to normalcy.

Strong ongoing vaccine safety monitoring programs in Canada

Canadian adults and adolescents have shown great confidence in the COVID-19 vaccine program due to the work carried out by Canadian doctors, public health officials, nurses, researchers, and allied health professionals. As vaccines continue to be rolled out, vaccine safety remains a top priority in Canada. This country has several robust and long-standing safety surveillance systems in place to monitor Adverse Events Following Immunization (AEFIs). A number of other, COVID-19-specific, safety surveillance projects are also underway, several supported by the CITF. Among the long-standing ones, Canada’s Immunization Monitoring Program ACTive (IMPACT), is a pediatric hospital-based national active surveillance network for AEFIs and selected infectious diseases that are, or will be, vaccine-preventable. Additionally, the long-running Canadian Vaccine Safety (CANVAS) Network that monitors the safety of seasonal influenza vaccines, has pivoted to also monitor COVID-19 vaccine safety (CANVAS-COVID) in adolescents and adults, and recently extended this to children under 12 years old. The IMPACT and CANVAS active surveillance systems collaborate and work closely with health providers and provincial, territorial, and federal health authorities as well as global partners to identify and verify potential AEFIs in real-time. These networks will closely monitor COVID-19 immunization among young children as they have for adolescents and adults.

Adverse events following immunizations  are rare

From our current understanding of the adverse events (or AEFIs) following COVID-19 vaccines the benefits of vaccinating children against the disease outweigh any potential risks. Though the COVID-19 vaccine trials in children aged 5-11 have not been large, the vaccines have been well tolerated by children and the reported AEFIs have been consistent with vaccinations for other diseases. In addition, the percentage of 5–11-year-olds who developed a systemic AEFI was lower than the percentage reported in the 16-25-year-old group (Walter, 2021).

Higher chance of myocarditis/pericarditis from infection than from vaccines

Early in the COVID-19 immunization program, myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the sac holding the heart) were observed, most commonly among young adult males after the second dose. As per the CDC, 40.6 cases of myocarditis have been reported per million second doses of the mRNA vaccines in 12–19-year-olds (Gargano J. W, 2021). On the other hand, researchers from the National Institutes of Health estimate that myocarditis post infection with SARS-CoV-2 may be as high as 450 per million in under 20-year-olds (Singer M. E, 2021, pre-print). Collectively, this evidence suggests that without vaccination, children are six to 10 times more likely to be affected by myocarditis. Furthermore, extensive analyses by the CDC and by researchers in other countries have shown that mRNA vaccine-associated myocarditis/pericarditis is rare, generally mild, and resolves quickly. In fact, severe myocarditis/pericarditis is much more common following SARS-CoV-2 infection (Curt 2021, Mendel 2021, Mevorach Dror, 2021, Witberg Guy, 2021, Simone Anthony, 2021). Additionally, cases of myocarditis/pericarditis are seen most frequently in older adolescents, with lower rates in the 12-to-15 year age group. Therefore, the risk to children younger than 12 may be even lower.  Further evidence indicates that symptoms related to vaccine-induced myocarditis/pericarditis resolve faster, without the use of additional medication to manage symptoms compared to myocarditis/pericarditis caused by COVID-19 (Patel T, 2021).

Mass vaccination has been saving lives for decades

Mass immunization campaigns are not new. Globally, immunization is recognized as one of the most important and cost-effective public health interventions available (WHO). Vaccine-preventable diseases such as measles and polio have been radically reduced by way of immunization campaigns around the world, and the Public Health Agency of Canada estimates that immunization has probably saved more lives in Canada in the last 50 years than any other health intervention (PHAC; Greenwood 2014). While it is understandable for parents to have concerns when new pediatric vaccines are introduced, the history of vaccination provides evidence that vaccines are a very safe and effective way to address preventable illnesses.


This pandemic has been met with an unprecedented global effort and real-time data sharing that has led to the development of very safe and effective vaccines, that continue to be monitored globally, and in Canada, by rigorous surveillance programs. With all this evidence, the National Advisory Committee on Immunization (NACI), the Canadian body that provides recommendations on vaccine use, has recommended that Canadian children between the ages of 5 and 11 may be vaccinated against COVID-19. Looking at the evidence, the benefits of vaccination outweigh the risks, especially as new variants of concern such as Omicron continue to challenge pandemic management. This is an opportunity to allow our kids to fully engage with the larger world once again.


  1. Lee P-I, Hu Y-L, Chen P-Y, Huang Y-C, Hsueh P-R. Are children less susceptible to COVID-19? J Microbiol Immunol Infect. 2020;53(3):371-2.
  2. Feldstein LR, Rose EB, Horwitz SM, Collins JP, Newhams MM, Son MBF, et al. Multisystem Inflammatory Syndrome in U.S. Children and Adolescents. N Engl J Med. 2020;383(4):334-46.
  3. Vella LA, Rowley AH. Current Insights Into the Pathophysiology of Multisystem Inflammatory Syndrome in Children. Curr Pediatr Rep. 2021:1-10.
  4. Eyre DW, Taylor D, Purver M, Chapman D, Fowler T, Pouwels KB, et al. The impact of SARS-CoV-2 vaccination on Alpha & Delta variant transmission. medRxiv. 2021:2021.09.28.21264260.
  5. Valentine R, Valentine D, Valentine JL. Investigating the relationship of schools reopening to increases in COVID-19 infections using event study methodology: The case of the Delta variant. J Public Health (Oxf). 2021.
  6. Jackson H. Children under 12 now account for highest number of new COVID-19 infections in Canada: PHAC. CTV News; 2021. p.
  7. Canada Go. COVID-19 vaccination in Canada 2021 [Available from:
  8. Laverty M SM, Squires SG, Ahmed MA, Eisenbeis L, Lee SJ, Des Cormiers A, Li YA. . Multisystem inflammatory syndrome in children in Canada. Can Commun Dis Rep 2021;47(11):461-5.
  9. Cost KT, Crosbie J, Anagnostou E, Birken CS, Charach A, Monga S, et al. Mostly worse, occasionally better: impact of COVID-19 pandemic on the mental health of Canadian children and adolescents. Eur Child Adolesc Psychiatry. 2021:1-14.
  10. Li X, Vanderloo LM, Maguire JL, Keown-Stoneman CDG, Aglipay M, Anderson LN, et al. Public health preventive measures and child health behaviours during COVID-19: a cohort study. Can J Public Health. 2021;112(5):831-42.
  11. Study CC. COVID-19 Rapid Results 2021 [Available from:
  12. Walter EB, Talaat KR, Sabharwal C, Gurtman A, Lockhart S, Paulsen GC, et al. Evaluation of the BNT162b2 Covid-19 Vaccine in Children 5 to 11 Years of Age. New England Journal of Medicine. 2021.
  13. Chia PY, Xiang Ong SW, Chiew CJ, Ang LW, Chavatte J-M, Mak T-M, et al. Virological and serological kinetics of SARS-CoV-2 Delta variant vaccine-breakthrough infections: a multi-center cohort study. medRxiv. 2021:2021.07.28.21261295.
  14. Singanayagam A, Hakki S, Dunning J, Madon KJ, Crone MA, Koycheva A, et al. Community transmission and viral load kinetics of the SARS-CoV-2 delta (B.1.617.2) variant in vaccinated and unvaccinated individuals in the UK: a prospective, longitudinal, cohort study. Lancet Infect Dis. 2021.
  15. Prevention UCfDCa. COVID Tracker: Demographic Characteristics of People Receiving COVID-19 Vaccinations in the United States 2021 [Available from:
  16. Sadarangani M, Marchant A, Kollmann TR. Immunological mechanisms of vaccine-induced protection against COVID-19 in humans. Nature Reviews Immunology. 2021;21(8):475-84.
  17. Skowronski DM, Setayeshgar S, Zou M, Prystajecky N, Tyson JR, Sbihi H, et al. Comparative single-dose mRNA and ChAdOx1 vaccine effectiveness against SARS-CoV-2, including early variants of concern: a test-negative design, British Columbia, Canada. medRxiv. 2021:2021.09.20.21263875.
  18. Gargano JW, Wallace M, Hadler SC, Langley G, Su JR, Oster ME, et al. Use of mRNA COVID-19 Vaccine After Reports of Myocarditis Among Vaccine Recipients: Update from the Advisory Committee on Immunization Practices – United States, June 2021. MMWR Morb Mortal Wkly Rep. 2021;70(27):977-82.
  19. Singer ME, Taub IB, Kaelber DC. Risk of Myocarditis from COVID-19 Infection in People Under Age 20: A Population-Based Analysis. medRxiv. 2021.
  20. Mevorach D, Anis E, Cedar N, Bromberg M, Haas EJ, Nadir E, et al. Myocarditis after BNT162b2 mRNA Vaccine against Covid-19 in Israel. New England Journal of Medicine. 2021.
  21. Witberg G, Barda N, Hoss S, Richter I, Wiessman M, Aviv Y, et al. Myocarditis after Covid-19 Vaccination in a Large Health Care Organization. New England Journal of Medicine. 2021.
  22. Simone A, Herald J, Chen A, Gulati N, Shen AY-J, Lewin B, et al. Acute Myocarditis Following COVID-19 mRNA Vaccination in Adults Aged 18 Years or Older. JAMA Internal Medicine. 2021.
  23. Daniels CJ, Rajpal S, Greenshields JT, Rosenthal GL, Chung EH, Terrin M, et al. Prevalence of Clinical and Subclinical Myocarditis in Competitive Athletes With Recent SARS-CoV-2 Infection: Results From the Big Ten COVID-19 Cardiac Registry. JAMA Cardiology. 2021;6(9):1078-87.
  24. Patel T, Kelleman M, West Z, Peter A, Dove M, Butto A, et al. Comparison of MIS-C Related Myocarditis, Classic Viral Myocarditis, and COVID-19 Vaccine related Myocarditis in Children. medRxiv. 2021:2021.10.05.21264581.
  25. Organization WH. Vaccines and Immunizations. Health Topics. Geneva: World Health Organization; 2021. p.
  26. Greenwood B. The contribution of vaccination to global health: past, present and future. Philos Trans R Soc Lond B Biol Sci. 2014;369(1645):20130433-.