Abstract
The emergence of SARS-CoV-2 variants that are more resistant to antibody-mediated neutralization pose a new hurdle in combating the COVID-19 pandemic. Although vaccines based on the original Wuhan sequence have been shown to be effective at preventing COVID-19, their efficacy is likely to be decreased against more neutralization-resistant variants-of-concern (VOC), in particular, the Beta variant originating in South Africa. We assessed, in mice, rabbits, and non-human primates, whether a third vaccination with experimental Wuhan-based Spike vaccines could alleviate this problem. Our data show that a third immunization improves neutralizing antibody titers against the variants-of-concern, Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), and Delta (B.1.617.2). After three vaccinations, the level of neutralization against Beta was similar to the level of neutralization against the original strain after two vaccinations, suggesting that simply providing a third immunization could nullify the reduced activity of current vaccines against VOC.
Highlights
The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains to present a major burden on society, with more than 250 million people infected since the start of the pandemic and around 5 million SARS-CoV-2 related deaths as of November 1, 2021
The main component of vaccines is the SARS-CoV-2 spike (S), which elicits neutralizing antibody (NAb) responses that protect against infection[1]
The U.S Food and Drug Administration (FDA), European Medicines Agency (EMA), and other regulatory agencies have approved several effective vaccines containing S based on the virus lineage that originated in Wuhan[2,3,4,5] and multiple vaccines are being rolled out in large vaccination campaigns[6,7,8,9]
Summary
The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains to present a major burden on society, with more than 250 million people infected since the start of the pandemic and around 5 million SARS-CoV-2 related deaths as of November 1, 2021 (https://covid19.who.int/). The neutralization titers against B.1 reached a mean titer of 365 2 weeks after the priming vaccination, while the titers against Alpha and Gamma were slightly higher (mean titers of 519 and 703, respectively) and the titer against Delta was twofold lower (mean titer of 171).
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