GRADE for Moderna COVID-19 Vaccine for Children Aged 6 Months–5 Years

A Grading of Recommendations, Assessment, Development and Evaluation (GRADE) review of the evidence for benefits and harms for Moderna coronavirus disease 2019 (COVID-19) vaccine for children aged 6 months­-­­5 years was presented to the Advisory Committee for Immunization Practices (ACIP) on June 18, 2022. GRADE evidence type indicates the certainty in estimates from the available body of evidence. Evidence certainty ranges from type 1 (high certainty) to type 4 (very low certainty) [1].

The policy question was, “Should vaccination with Moderna COVID-19 vaccine (2 doses, 25 µg) be recommended for children 6 months-5 years of age during an Emergency Use Authorization?” The potential benefits pre-specified by the ACIP COVID-19 Vaccines Work Group included prevention of symptomatic laboratory-confirmed COVID-19 (critical), hospitalization due to COVID-19 (important), multisystem inflammatory syndrome in children (MIS-C) (important), and asymptomatic SARS-CoV-2 infection (important). The two pre-specified harms were serious adverse events (SAEs) (critical) and reactogenicity grade ≥3 (important).

A systematic review of evidence on the efficacy and safety of a two-dose regimen of Moderna COVID-19 vaccine among children aged 6 months–5 years was conducted. The quality of evidence from one Phase II/III randomized controlled trial was assessed using a modified GRADE approach [2].

A lower risk of symptomatic COVID-19 was observed with vaccination compared with placebo (relative risk [RR]: 0.62; 95% confidence interval [CI]: 0.49, 0.79, evidence type 1). Immunobridging was also assessed. In both age groups, 6–23 months and 2–5 years, the immune response to vaccine was non-inferior to that observed in adults ages 18-25 years (6–23 months GMR: 1.28; 95% CI: 1.12, 1.47; 2–5 years GMR: 1.01; 95% CI: 0.88, 1.17; evidence type 2). There was also a lower risk of asymptomatic SARS-CoV-2 infection seen in the vaccine group compared with the placebo group, however the confidence interval crossed the line of no effect (RR: 0.84; 95% CI: 0.60,1.19; evidence type 3). The available data indicated that SAEs were more common in vaccine recipients, but certainty in the estimate was very low (RR 2.67; 95% CI: 0.80, 8.84; evidence type 4). Two serious adverse events in one participant were determined by the Food and Drug Administration (FDA) as potentially related to the vaccination. No specific safety concerns were identified among vaccine recipients aged 6 months–5 years. Reactogenicity grade ≥3 was associated with vaccination (RR 1.87; 95% CI: 1.44, 2.42); evidence type 1). About 7.7% of vaccine recipients and 4.4% of placebo recipients reported any grade ≥3 local or systemic reactions following either dose 1 or dose 2.