A Study to Investigate the Immunogenicity and Safety of mRNA COVID-19 Variant-containing Vaccine Formulations

This study uses a master protocol with a generic study design to allow flexibility in evaluating immunogenicity of variant-containing formulations of the mRNA-1273 COVID-19 vaccine. As different variant-containing vaccine formulations will be evaluated, each study intervention will be described in the subprotocol. For each evaluation of an updated variant vaccine or age group, a new subprotocol will be generated. Reported outcome measures are based upon master protocol. Not all reported outcome measures may be applicable to each subprotocol.