Neutralizing antibody responses 300 days after SARS‐CoV‐2 infection and induction of high antibody titers after vaccination

Neutralizing antibodies against SARS‐CoV‐2 are important to protect against infection and/or disease. Using an assay to detect antibodies directed against the receptor binding domain (RBD) of SARS‐CoV‐2 Spike, we identified individuals with SARS‐CoV‐2 infection after an outbreak at a local health institution. All but one COVID‐19 patient developed detectable anti‐RBD antibodies and 77% had virus neutralizing antibody titers of >1:25. Antibody levels declined slightly over time. However, we still detected virus neutralizing antibody titers in 64% of the COVID‐19 patients at >300 days after infection, demonstrating durability of neutralizing antibody levels after infection. Importantly, full COVID‐19 vaccination of these individuals resulted in higher antibody titers compared to fully vaccinated individuals in the absence of prior infection. These data demonstrate long‐lived antibody‐mediated immunity after SARS‐CoV‐2 infection, and a clear benefit of two vaccine doses for recovered individuals.