mRNA-1273 Vaccine-elicited Neutralization of SARS-CoV-2 Omicron in Adolescents and Children

BACKGROUND: The highly transmissible severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) Omicron variant is a global concern. This study assessed the neutralization activity of two-dose regimens of mRNA-1273 vaccination against Omicron in adults, adolescents and children. METHODS: Neutralizing activity against the Omicron variant was evaluated in serum samples from adults (≥18 years) in the phase 3, Coronavirus Efficacy (COVE) and from adolescents (12–17 years) in the TeenCOVE trials following a two-dose regimen of 100 μg mRNA-1273 and from children (6-<12 years) in the KidCOVE trial administered two doses of 50 μg mRNA-1273. Neutralizing antibody geometric mean ID(50) titers (GMT) were measured using a lentivirus-based pseudovirus neutralizing assay at day 1 and 4 weeks (day 57) following the second mRNA-1273 dose, compared with wild-type (D614G). RESULTS: At 4 weeks following a second dose of mRNA-1273 (100 μg), the GMT was reduced 28.8-fold compared with D614G in adults (≥18 years). In adolescents (12–17 years), the GMT was 11.8-fold lower than D614G, 4 weeks after a second dose of mRNA-1273 (100 μg), and compared with adults, were 1.5- and 3.8-fold higher for D614G and the Omicron variant, respectively. In children (6-<12 years), 4 weeks post-second dose of 50 μg mRNA-1273, Omicron GMTs were reduced 22.1-fold versus D614G and were 2.0-fold higher for D614G and 2.5-fold higher for Omicron compared with adults. CONCLUSIONS: A two-dose regimen of 100 μg mRNA-1273 in adolescents and of 50 μg in children elicited neutralization responses against the Omicron variant that were reduced compared with the wild-type D614G, and numerically higher than those in adults.