Three-month Antibody Persistence of a Bivalent Omicron-containing Booster Vaccine Against COVID-19

Abstract

<title>Abstract</title> We previously presented day 29 interim safety and immunogenicity results from a phase 2/3 study comparing the Omicron-BA.1-containing bivalent vaccine mRNA-1273.214 (50-µg) to the 50-µg mRNA-1273 booster in adults who previously received the mRNA-1273 primary series (100-µg) and mRNA-1273 first booster (50-µg) dose. Here we present day 91 post-booster results. Participants were sequentially enrolled to receive 50-µg of mRNA-1273 (n = 376) or mRNA-1273.214 (n = 437) as second booster doses. In participants with no pre-booster severe acute respiratory syndrome coronavirus 2-infection (SARS-CoV-2), mRNA-1273.214 elicited Omicron-BA.1-neutralizing antibody titers that were significantly higher (964.4 [834.4-1114.7]) than those of mRNA-1273 (624.2 [533.1-730.9]) and similar between boosters against ancestral SARS-CoV-2 at day 91. mRNA-1273.214 also induced higher binding antibody responses against Omicron BA.1 and alpha, gamma and delta variants than mRNA-1273. Safety profiles were similar for both vaccines. The Omicron-BA.1 bivalent vaccine induced improved antibody persistence compared to mRNA-1273.