Originally published by 2 Minute Medicine® (view original article). Reused on AccessMedicine with permission.

1. A three-dose series of BNT162b2 was efficacious in eliciting an immune response and protecting children between six months and four years of age against coronavirus disease 2019 (COVID-19) infection.

2. The vaccine was evaluated to be safe with the majority of adverse events rated as mild to moderate.

Evidence Rating Level: 1 (Excellent)

Study Rundown:

COVID-19 affects people of all ages, including young children. Although it is generally mild in this age group, severe disease leading to hospitalizations and multisystem inflammatory syndrome can still occur. Novel variants have also been associated with increased rates of hospitalization and transmissions. Existing mRNA-based vaccines, proven to be effective in preventing infection and severe disease, have not been adequately assessed in clinical trials in children younger than five years of age. The current study reported findings from a completed phase one and ongoing phase two/three trial to assess the safety, immunogenicity, and efficacy of the BNT162b2 vaccine in children between six months and four years of age. In contrast to the 30 microgram dose administered to older children and adults, these participants were given a three-dose series of 3 micrograms of BNT162b2. Overall, it was shown that BNT162b2 led to a strong antibody response as compared to a placebo. Correspondingly, the observed efficacy of BNT162b2 with respect to symptomatic COVID-19 was significantly increased. The safety profile was also favorable, with reactogenicity events being mainly mild to moderate, with none reaching severe. The incidence of fever was low across all age groups and comparable to the placebo. As a limitation, the trial was not powered to assess efficacy against severe disease or specific variants.

In-Depth [randomized controlled trial]:

This study reported results from a phase one trial of the mRNA-based BNT162b2 COVID-19 vaccine among healthy children six months to four years of age. A total of 1,178 children six months to less than two years of age and 1,835 children two to four years of age were randomized in a 2:1 ratio to receive three doses of BNT162b2 or placebo. Immunogenicity outcome was assessed in participants without serologic or virologic evidence of previous SARS-CoV-2 infection and measured in neutralizing geometric mean titers (GMTs). Safety was assessed via reactogenicity events within seven days after each dose, adverse events, and severe events through to six months after the final dose. Geometric mean ratios of neutralizing GMTs elicited by three doses of BNT162b2 among children six months to less than two years of age and children two to four years of age relative to GMTs observed after dose two in individuals 16 to 25 years of age were 1.19 (95% Confidence Interval [CI], 1.00 to 1.42) and 1.30 (95% CI, 1.13 to 1.50), respectively. The observed efficacy of BNT162b2 against symptomatic COVID-19 across the entire participant pool was 73.2% (95% CI, 43.8 to 87.6), based on 34 recorded cases (13 in the BNT162b2 group and 21 in the placebo group). Lastly, BNT162b2 showed favorable safety outcomes, with the most common adverse events being local reactions, fever, irritability, and fatigue. Severe reactions and adverse events were infrequent; none reached grade four severity. In summary, these results demonstrated the safety and efficacy of a three-dose regimen of BNT162b2 for children between six months and four years of age for preventing COVID-19.

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