On November 19, 2021, the Pfizer-BioNTech COVID-19 vaccine (Comirnaty) was authorized in Canada for use in children 5 to 11 years of age. This document summarizes information specific to this age group.
For detailed information on COVID-19 vaccine for older children, immunocompromised children, contraindications and precautions, immunization stress-related responses, and vaccine hesitancy, as well as on mRNA vaccines, seeCPS关于12岁及以上儿童的Covid-19疫苗的CPS声明. For sources of data cited in the present document, see References at the end.
COVID-19 and children 5 to 11 years of age
Children with SARS-CoV-2 infection generally present with mild illness or remain asymptomatic. Severe outcomes such as hospitalization, ICU admission, and death are rare. Nevertheless, some children develop severe disease and require hospitalization. In Canada, severe outcomes such as hospitalization and death are very infrequent in children, occurring in <0.3% and <0.002% respectively of confirmed SARS-CoV-2 cases in children aged 5 to 11 years old. As of November 9, 2021, children in this age group represented 7.5% of confirmed SARS-CoV-2 infections, 0.3% of COVID-19-associated hospitalizations, 0.3% of COVID-19-associated ICU admissions, and 0.007% of COVID-19 deaths. Recently, children 5 to 11 years old have become the population with the highest incidence of confirmed SARS-CoV-2 infections, although their rate of hospitalization has remained low.
孩子们多系统正无穷发展的风险lammatory syndrome in children (MIS-C), which is a serious though uncommon condition associated with recent SARS-CoV-2 infection. MIS-C is estimated to affect between 0.5% and 3.1% of all children diagnosed with SARS-CoV-2 infection, and between 0.9% and 7.6% of hospitalized paediatric COVID-19 patients. In Canada, 272 cases of MIS-C in individuals 0 to 19 years of age had been reported as of October 16, 2021. Their median age was 6 years, with 40% of cases occurring in children aged 5 to 11 years old. Most MIS-C cases recover fully, and no MIS-C-associated deaths have been reported in Canada to date.
Children with certain underlying chronic medical conditions are known to be at increased risk for severe COVID-19 disease, but evidence regarding clinical risk factors specific to the 5 to 11 year old age group is limited. Canadian surveillance data have indicated that 39% of children younger than 18 years old who were hospitalized due to COVID-19 had at least one underlying comorbidity. Risk factors for more severe disease in children included obesity, chronic neurological conditions, chronic lung disease other than asthma, and immunodeficiency. Studies of children ≤18 years in the United States identified obesity, asthma, chronic lung disease, congenital cardiac disease, neurodevelopmental disorders, some mental health conditions, and type 1 diabetes as risk factors for developing severe COVID-19 disease. One multicentre study from Europe reported an increased risk of ICU admission for COVID-19 in individuals ≤18 years old with chronic pulmonary disease, congenital heart disease, or neurological disorders. In a systematic review of children with severe COVID-19 disease requiring mechanical ventilation, 75% had comorbidities, the most common being chronic cardiac disease, immunosuppression, chronic respiratory disease, and obesity. Finally, recent cohort studies in children and adolescents hospitalized for COVID-19 have identified the presence of multiple comorbidities, obesity, neurological disorders, feeding tube dependence, Down syndrome, immunocompromising conditions, and living in congregate settings as independent risk factors for severe COVID-19.
Along with the risks to physical health posed by the SARS-CoV-2 infection, the pandemic and the public health response to it have had significant adverse indirect effects. Disruptions in family routines, school and other educational activities, play, and sports, as well as separation from friends, grandparents, and other close family members have affected the mental health and physical well-being of children in Canada. In addition, the COVID-19 pandemic, and the response to it, may further exacerbate social inequities among racialized and Indigenous communities, refugees and other newcomers to Canada, persons living in low-income settings, as well as children with disabilities.
Children also transmit SARS-CoV-2, although their relative importance in transmission in different settings is not yet clear. One Ontario study of transmission in households has reported that children aged 0 to 3 years have greater odds of transmitting to household contacts than older children.
COVID-19 vaccine for children 5 to 11 years of age
的Pfizer-BioNTech COVID-19 mRNA vaccine (Comirnaty) for the 5- to- 11-year-old age group is different from the Pfizer-BioNTech COVID-19 vaccine for children aged 12 years and older:
的dose is different. Each dose is 0.2 mL and contains 10 mcg of SARS-CoV-2 spike protein mRNA (compared with a dose of 0.3 mL containing 30 mcg of mRNA in the vaccine for older children).
A buffer component, tromethamine, has been added to facilitate storage. Tromethamine (also known as ‘trometamol’ or ‘tris’) is present in the Moderna COVID-19 vaccine and has been used for many years in some routine childhood vaccines as well as in other injectable medications, without safety concerns. Allergy to tromethamine has been reported but is extremely rare.
In the clinical trial of the Pfizer-BioNTech COVID-19 vaccine in children aged 5 to 11 years old, 1518 children who received the vaccine and 750 who received placebo have been followed for a minimum of 2 months. A further cohort of 1591 children who received the vaccine in this study have been followed for adverse effects for a median of 2.4 weeks. Interim findings indicated that the vaccine’s efficacy against symptomatic disease and its immunogenicity are similar to those reported in studies of COVID-19 vaccine in adolescents and young adults. Local reactions were very common, mostly mild to moderate in severity and more frequent than in older children. Systemic events occurred more frequently after the second dose and were predominantly fatigue, headaches, muscle pain, chills, fever, and joint pain. Most systemic events were mild or moderate in severity. Systemic reactogenicity in 5- to 11-year-olds was lower than that observed for adolescents and young adults. There were no cases of myocarditis or pericarditis or any other serious adverse event.
Any uncommon, rare, or very rare adverse event that could occur at the frequency of less than 1 in 1000 vaccine recipients would not be detected with a trial of this size. The studies described above are ongoing, and all the children involved will be followed for a full 2 years after their second dose of vaccine. Intensive post-marketing surveillance for adverse effects is ongoing in Canada and elsewhere, and the National Advisory Committee on Immunization (NACI) will continue to review emerging evidence closely.
Rare cases of myocarditis and/or pericarditis have been reported following administration of the Pfizer-BioNTech vaccine (30 mcg) in adolescents and young adults, most commonly after the second dose and more often in males than females. Emerging Canadian safety surveillance data suggest that a longer interval between the first and second dose of an mRNA COVID-19 vaccine may reduce the risk of myocarditis/pericarditis. Data from the United States further suggest that the risk of myocarditis/pericarditis following mRNA COVID-19 vaccination may be higher in adolescents aged 16 to 17 years then in younger adolescents aged 12 to 15 years.
At time of writing, the risk of myocarditis/pericarditis in children 5 to 11 years old following immunization with the 10 mcg dose of the Pfizer-BioNTech vaccine is unknown. However, in general, the occurrence of myocarditis unrelated to COVID-19 vaccine is less common in children this age than in older adolescents and young adults.
NACI has recommended that a primary series of two doses of the Pfizer-BioNTech COVID-19 vaccine (10 mcg per dose) may be offered to children 5 to 11 years of age, with a dosing interval of at least 8 weeks between the first and second dose. Children with moderate or severe immunocompromise should receive a primary series of three doses, with the third dose given at least 28 days after the second.
NACI’s recommendation is more tentative than that of the Advisory Committee on Immunization Practices in the United States, which recommends the vaccine for all children 5 to 11 years old and states that the benefits of vaccination outweigh the risks. Assessment of benefits and risks will vary from country to country depending on COVID-19 epidemiology.
Factors to be considered when deciding about vaccination against COVID-19 include:
SARS-Cov-2 infection in children 5 to 11 years of age is usually asymptomatic or causes mild disease. Some children, including previously healthy children, will develop serious infection or MIS-C.
Studies have shown that vaccine efficacy, immunology, and safety are comparable to results found in older children and adults. No serious adverse effects have been detected to date.
的dose of mRNA in the vaccine for children 5 to 11 years old is one-third of that in the vaccine used for individuals 12 years of age and older.
Local COVID-19 epidemiology: Current high or increasing rate of COVID-19; local outbreaks.
Risk of exposure: In-person school attendance, current COVID-19 outbreaks in schools.
Need for proof of COVID-19 vaccination for travel or other activities.
的Pfizer-BioNTech COVID-19 vaccine is authorized in Canada to be administered at a dosing interval of 21 days. In adults, the evidence now suggests that longer intervals between the first and second doses result in a stronger immune response and higher vaccine effectiveness that is expected to last longer, compared with shorter intervals. The data further suggest that an extended interval between doses may be associated with reduced risk for developing myocarditis/pericarditis after the second dose. Therefore, NACI recommends a dosing interval of 8 weeks.
For children with a previous history of MIS-C, vaccination should be postponed until clinical recovery is complete or ≥90 days post-diagnosis, whichever is longer.
Regarding co-administration with other vaccines:
NACI states that thorough post-marketing safety surveillance will be required to detect adverse events following immunization that may occur in children 5 to 11 years of age. It would be prudent to wait for a period of at least 14 days BEFORE or AFTER the administration of another vaccine before administrating a COVID-19 vaccine. This suggested waiting period between vaccines is precautionary and feasibility may be challenging for both health care providers and parents. Concomitant administration or a shortened interval between vaccines may be warranted on an individual basis in some circumstances at the clinical discretion of the health care provider.
的CPS recommends that COVID-19 vaccine be offered simultaneously with other required vaccines除非有保证及时给予其他疫苗不会受到损害. Many children have missed routine immunizations during this pandemic.
Children who receive the 10 mcg Pfizer-BioNTech COVID-19 vaccine for their first dose and turn 12 years old before their second dose may receive the 30 mcg per dose Pfizer-BioNTech COVID-19 vaccine. However, if the second dose of 10 mcg is given instead, the dose is considered sufficient.
Prophylactic oral analgesics or antipyretics, such as acetaminophen or ibuprofen, should not be routinely used before or at the time of vaccination, but may be considered for the management of pain or fever after vaccination. Families may also be introduced to the CARD system for help in coping with fear and anxiety around injections.
Paediatricians and other health care professionals caring for children should be prepared to address the concerns and fears of parents and children regarding this new vaccine, including concerns about myocarditis.
的second dose of COVID-19 vaccine should be deferred in children diagnosed with myocarditis or pericarditis following their first dose of the vaccine until more information is available.
Children with a history of myocarditis unrelated to COVID-19 vaccination should consult their physicians for advice about receiving an mRNA COVID-19 vaccine. If the myocarditis diagnosis is remote and if they are no longer followed clinically for cardiac issues, they may receive the vaccine.
COVID-19 vaccination program planning and implementation should ensure equitable access to information and services, and minimize inequities in vaccine availability, acceptance, and uptake based on socioeconomic status.
Parents of children aged 5 to 11 years must be supported and respected in their decisions regarding COVID-19 vaccinations for their children, whatever decisions they make, and are not to be stigmatized for these decisions.
In addition to vaccination, it is important that everyone, regardless of vaccination status, continue to follow recommended public health measures such as masking and social distancing.
CANADIAN PAEDIATRIC SOCIETY, INFECTIOUS DISEASES AND IMMUNIZATION COMMITTEE (2020-2021)
Members:Michelle Barton-Forbes MD; Ari Bitnun MD; Sergio Fanella MD; Laura Sauvé MD (Chair); Raphael Sharon MD (Board Representative); Karina Top MD
Liaisons:Ari Bitnun MD, Canadian Pediatric and Perinatal HIV/AIDS Research Group; Fahamia Koudra MD, College of Family Physicians of Canada; Marc Lebel MD, IMPACT (Immunization Monitoring Program, ACTive); Yvonne Maldonado MD, Committee on Infectious Diseases, American Academy of Pediatrics; Dorothy L. Moore MD, National Advisory Committee on Immunization (NACI); Marina Salvadori MD, Public Health Agency of Canada; Isabelle Viel-Thériault MD, Committee to Advise on Tropical Medicine and Travel (CATMAT), Public Health Agency of Canada
Disclaimer:的recommendations in this position statement do not indicate an exclusive course of treatment or procedure to be followed. Variations, taking into account individual circumstances, may be appropriate. Internet addresses are current at time of publication.