1. Two doses of the Moderna coronavirus disease 2019 (COVID-19) vaccine were not associated with a significant increase in serious adverse events in children six months to five years old.

2. Two doses of the Moderna vaccine were associated with immune responses in children that were noninferior to those in young adults.

Evidence Rating Level: 1 (Excellent)

Study Rundown: The Moderna (mRNA-1273) vaccine is a COVID-19 messenger RNA vaccine that has been found to be safe and efficacious in preventing illness from SARS-CoV-2 infections in adults, adolescents, and older children (six to 11 years of age). It is approved for use in the United States, and though efficacy is lower against the omicron variant than against other variants, two Moderna injections have been shown to continue to protect against hospitalization and death. However, there is a gap in knowledge as to understanding the safety and efficacy of the Moderna vaccine in children six months to five years of age. Overall, this study found that two injections of the Moderna vaccine had acceptable reactogenicity, safety, and effectiveness during a period when omicron was the predominant circulating variant. This study was limited by including generally healthy children and children with stable medical conditions. It was also underpowered to detect rare adverse events, though widespread use of the vaccine in children after authorization may reveal other less frequent or more serious adverse events.

Click to read the study in NEJM

Relevant Reading: Antibody Persistence through 6 Months after the Second Dose of mRNA-1273 Vaccine for Covid-19

In-Depth [randomized controlled trial]: This observer-blinded, randomized, placebo-controlled trial was conducted across 79 sites in the United States and eight sites in Canada. Patients who were six months to five years of age and healthy or with stable chronic conditions such as asthma or diabetes mellitus were eligible for the study. The primary outcome measured was serum antibody geometric mean concentrations and serologic responses among these children as compared with those among young adults who also received two injections of the Moderna vaccine. Outcomes in the primary analysis were assessed via per-protocol analysis and compared the mean concentrations with the Clopper-Pearson method and Miettinen-Nurminen methods. Based on the primary analysis, on day 57, neutralizing antibody geometric mean concentrations were 1,410 (95% Confidence Interval [CI], 1,272 to 1,563) among two to five-year-olds and 1,781 (95% CI, 1,616 to 1,962) among six to 23-month-olds, as compared with 1,391 (95% CI, 1263 to 1531) among young adults. This was deemed to meet the noninferiority criteria for immune responses across both age cohorts. Additionally, the estimated vaccine efficacy against COVID-19 was 36.8% (95% CI, 12.5 to 54.0) among two to five-year-olds and 50.6% (95% CI, 21.4 to 68.6) among six to 23-month-olds. Overall, this study demonstrated that the Moderna mRNA COVID-19 vaccine is safe and effective for use in children six months to five years of age.

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