Formica N, Mallory R, Albert G, et al. - Researchers designed this study to determine the dosing regimen of NVX-CoV2373 that was immunogenic and linked with an acceptable safety and tolerability profile to move forward into late-phase efficacy studies.

• Either 1 or 2 intramuscular doses of 5-μg or 25-μg NVX-CoV2373 or placebo were administered to participants (n = 1,288) in 2 age groups (aged 18 to 59 and 60 to 84 years).

• There appeared predominantly mild to moderate reactogenicity after first and second vaccination with NVX-CoV2373; reactogenicity was of short duration (median < 3 days) and appeared at higher frequencies and intensity after second vaccination and with the higher dose.

• Older participants showed reactogenicity less frequently and at lower intensity.

• In both younger and older adults, the 2-dose regimen of 5-μg NVX-CoV2373 was immunogenic and well tolerated.

• In late-phase efficacy studies, researchers support using the lower-dose regimen.