The safety profile and efficacy of the Pfizer COVID-19 vaccine (BNT162b2) in children younger than 5 years old
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Reviewed by Dat Tien Nguyen, B.A, ScM.
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Posted on February 22nd, 2023
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In most cases, SARS-CoV-2 causes mild to moderate disease in children under the age of 5. However, there have been many severe infections in the form of multisystem inflammatory syndrome in children (MIS-C) which can lead to death. However, there is no research on the effectiveness and safety of the vaccine in young children. Thus, the pharmaceutical companies Pfizer and BioNTech had conducted a study to investigate the effect of the BNT162b2 vaccine in children below 5 years old.
The company had recently published their findings in the New England Journal of Medicine. During the 1st phase of the clinical trial, the researchers compare the safety between a 2-dose regimen of BNT162b2 containing 3 micrograms of antigen and a regimen with a higher antigen concentration of 10 micrograms. The comparison was done on a cohort of children between the age of 6 months and 2 years old and a cohort between the age of 2 and 5 years old. At the end of the initial phase, the 3 microgram dose was selected for the later studies. The phase 2 and 3 studies were conducted concurrently on a cohort of 1178 children between the age of 6 months and 2 years old and a cohort of 1835 children between the age of 2 and 5 years old. These children received either placebo or the BNT162b2 vaccine containing 3 micrograms of antigen. The second dose was administered after 21 days from the first, and the third dose was given 8 weeks after the second dose. These children were followed up for 1 month after each dose for the vaccine effectiveness, and 8 weeks after the 3rd dose for safety outcome. At the end of the study, the researchers concluded that the effectiveness of the BNT162b2 vaccine (3 micrograms formula) was 75.8% in children between the ages of 6 months and 2 years old, and 71.8% in children between the ages of 2 and 5 years old. Most of the adverse events reported by the were mild to moderate. Irritability was the most commonly reported event in the younger cohort, but there was little difference between the placebo and vaccine groups. Overall, there is no significant difference in the frequency of adverse events between the two groups. Throughout the study, the researchers did not detect any case of myocarditis, pericarditis, Bell’s palsy, or thromboembolic events.
The company had recently published their findings in the New England Journal of Medicine. During the 1st phase of the clinical trial, the researchers compare the safety between a 2-dose regimen of BNT162b2 containing 3 micrograms of antigen and a regimen with a higher antigen concentration of 10 micrograms. The comparison was done on a cohort of children between the age of 6 months and 2 years old and a cohort between the age of 2 and 5 years old. At the end of the initial phase, the 3 microgram dose was selected for the later studies. The phase 2 and 3 studies were conducted concurrently on a cohort of 1178 children between the age of 6 months and 2 years old and a cohort of 1835 children between the age of 2 and 5 years old. These children received either placebo or the BNT162b2 vaccine containing 3 micrograms of antigen. The second dose was administered after 21 days from the first, and the third dose was given 8 weeks after the second dose. These children were followed up for 1 month after each dose for the vaccine effectiveness, and 8 weeks after the 3rd dose for safety outcome. At the end of the study, the researchers concluded that the effectiveness of the BNT162b2 vaccine (3 micrograms formula) was 75.8% in children between the ages of 6 months and 2 years old, and 71.8% in children between the ages of 2 and 5 years old. Most of the adverse events reported by the were mild to moderate. Irritability was the most commonly reported event in the younger cohort, but there was little difference between the placebo and vaccine groups. Overall, there is no significant difference in the frequency of adverse events between the two groups. Throughout the study, the researchers did not detect any case of myocarditis, pericarditis, Bell’s palsy, or thromboembolic events.