The following were higher in the placebo group compared with the vaccine group by at least 1%: upper respiratory tract infection (12.2% vs 10.3%), COVID-19 (4.9% vs 3.5%), and otitis media (3.7% vs 2.6%). The following unsolicited adverse events were higher in the vaccine group compared with the placebo group by at least 1%: injection site lymphadenopathy (1.4% vs 0.2%) croup (1.3% vs 0.3%) diarrhea (3.2% vs 2.2%). In general, unsolicited adverse events experienced in the vaccine group were similar in nature and incidence to those in the placebo group. The overall incidence of unsolicited adverse events up to 28 days after any dose were similar in the vaccine group (49.3%) and the placebo group (48.2%) for participants ages 5-23 months. Adverse events in the vaccine group were similar in nature and incidence to those in the placebo group, with the exception of higher incidence of injection site erythema in the vaccine group compared to the placebo group (1.3% vs 0.2%) and COVID-19 in the placebo group compared to the vaccine group (5.5% vs 3.1%).

The overall incidence of unsolicited adverse events up to 28 days after any dose were similar in the vaccine group (40.0%) and the placebo group (37.5%) for participants ages 2 – 5 years. Systemic reactions in children ages 37 months – 5 years, Moderna mRNA-1273 COVID-19 vaccine and placebo Systemic reactions in persons ages 6–23 months, Moderna mRNA-1273 COVID-19 vaccine and placeboīGrade 3: prevents daily activity Grade 4: emergency room visit or hospitalization for severe pain at the injection site. The majority of reactions occurred within the first 2 days after dose 1 and dose 2, persisting for a median of 3 and 2 days for the 6-23 months and 2-5 age groups respectively. Upon further review, 3 of the 13 fever events were incorrectly reported as grade 4, given that none of these 3 participants recorded any elevated temperature resulting in 10 confirmed grade 4 fevers: 8 (0.3%) in the mRNA-1273 group and 2 (0.2%) in the placebo group in the 2-5 age group. There were 13 fever events >40☌ reported: 11 (0.4%) participants in the vaccine group and 2 (0.2%) in the placebo group among the 2 to 5-year-old-age group. Grade 4 solicited systemic adverse reactions were reported for fever (placebo: 1/585, 0.2% vaccine: 4/1758, 0.2%) in the 6-23 months age group. The majority of systemic events were mild or moderate in severity, but there was a higher occurrence of grade 3 or higher reactions in the vaccine group. The most common solicited systemic adverse reactions after any dose were irritability/crying and fatigue for participants 6-36 months and 37 months-5 years, respectively. Solicited systemic adverse reactions were most common in the vaccine group than the placebo group and after dose 2 compared to dose 1. Overall, the median onset of local reactions in the vaccine group was 1 day after either dose, with a median duration of 2 days. No grade 4 local reactions were reported. Redness and swelling were more common after dose 2. Injection site redness and swelling following either dose were reported less frequently. Axillary (or groin) swelling or tenderness was reported slightly more frequently in the younger age group than the older age group (9.3% vs 9.1% after dose 2). Axillary (or groin) swelling or tenderness was the second most frequently reported local reaction. After dose 1, the older age group reported pain more frequently than the younger age group (61.4% vs 37.4%) a similar pattern was observed after dose 2 (71.4% vs 46.2%). Pain at the injection site was the most frequent and severe reported solicited local reaction among vaccine recipients.

The frequency of local reactions was higher in the older age group (ages 2 to 5 years) than the younger age group (ages 6-23 months) (73.4% vs 54.4% after dose 2). Vaccine recipients reported higher rates of local reactions after dose 2 than dose 1. Local reactions were reported by the majority of vaccine recipients and at higher rates than placebo recipients. Persons Aged 6 Months – 5 Years Local Reactions

Moderna vaccine production timeline