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

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

Automated summary

The study found that neutralizing antibody responses against several variants of concern gradually declined after vaccination with the mRNA-1273 vaccine for the SARS-CoV-2 virus. However, boosting nonhuman primates with either homologous or heterologous mRNA-1273 vaccines after 6 months resulted in increased neutralizing antibody responses across all variants of concern, which lasted for at least 8 weeks after the boost. After being challenged with the SARS-CoV-2 Beta variant 9 weeks post-boost, viral replication was low to undetectable in bronchoalveolar lavage and significantly reduced in nasal swabs in all boosted animals, indicating the potential necessity for booster vaccinations to maintain immunity and protection.