Protection against SARS-CoV-2 Beta variant in mRNA-1273 vaccine–boosted nonhuman primates

Abstract

Neutralizing antibody responses gradually wane against several variants of concern (VOC) after vaccination with the SARS-CoV-2 vaccine mRNA-1273. We evaluated the immune responses in nonhuman primates that received a primary vaccination series of mRNA-1273 and were boosted ~6 months later with either homologous mRNA-1273 or heterologous mRNA-1273.β, which encompasses the spike sequence of the B.1.351 beta (β) variant. Following boost, animals had increased neutralizing antibody responses across all VOC, which was sustained for at least 8 weeks post-boost. Nine weeks following boost, animals were challenged with the SARS-CoV-2 β variant. Viral replication was low to undetectable in bronchoalveolar lavages and significantly reduced in nasal swabs in all boosted animals suggesting booster vaccinations may be required to sustain immunity and protection.