Changes in serum neutralizing antibody potency and breadth post SARS-CoV-2 mRNA vaccine boost

ABSTRACT

A better understanding of the durability and breadth of serum neutralizing antibody responses against multiple SARS-CoV-2 variants elicited by Covid-19 vaccines is crucial in addressing the current pandemic. In this study, we quantified the decay of serum neutralization antibodies (nAbs) after second and third doses of the original Covid-19 mRNA vaccine. Using an authentic virus neutralization assay, we found that decay half-lives of WA1- and Delta-nAbs were both ∼60 days post second and third vaccine dose. Unexpectedly, the durability of serum antibodies that neutralize three different Omicron subvariants (BA.1.1, BA.5, BA.2.12.1) was substantially better, with half-lives of ≥ 6 months. A booster dose of the original Covid-19 vaccine was also found to broaden antibody responses against SARS-CoV and four other sarbecoviruses, in addition to multiple SARS-CoV-2 strains. These findings suggest that repeated vaccinations with the Covid-19 vaccine may confer a degree of protection against future spillover of sarbecoviruses from animal reservoirs. Graphical abstract