Previously infected vaccinees broadly neutralize SARS-CoV-2 variants

Abstract

We compared the serum neutralizing antibody titers before and after two doses of the BNT162b2 COVID-19 vaccine in ten individuals who recovered from SARS-CoV-2 infection prior to vaccination to 20 individuals with no history of infection, against clinical isolates of B.1.1.7, B.1.351, P.1, and the original SARS-CoV-2 virus. Vaccination boosted pre-existing levels of anti-SARS-CoV-2 spike antibodies 10-fold in previously infected individuals, but not to levels significantly higher than those of uninfected vaccinees. However, neutralizing antibody titers increased in previously infected vaccinees relative to uninfected vaccinees against every variant tested: 5.2-fold against B.1.1.7, 6.5-fold against B.1.351, 4.3-fold against P.1, and 3.4-fold against original SARS-CoV-2. Our study indicates that a first-generation COVID-19 vaccine provides broad protection from SARS-CoV-2 variants in individuals with previous infection.

Figure 1.. Anti-SARS-CoV-2 antibody levels elicited by vaccination and natural infection.

(A) Half maximal effective concentration (EC50) of total pan-Ig antibodies specific to the spike RBD were measured by enzyme-linked immunosorbent assay (ELISA) in serum collected from donors previously infected with SARS-CoV-2 pre- and post-vaccination with the BNT162b2 vaccine. (B) EC50 of RBD-binding IgA. (C) EC50 of RBD-binding IgG. Statistical comparisons were made using the Wilcoxon rank-sum test. LOD denotes limit of detection.

Figure 2.. Immunity from natural SARS-CoV-2 infection boosted by subsequent vaccination broadens protection against variants of concern.

Neutralization of SARS-CoV-2 variants by pre-and post-vaccination sera collected from previously infected and naïve individuals. Shown are the results of a 50% focus reduction neutralization testing (FRNT50) for an early SARS- CoV-2 isolate USA-WA1/2020 (A) and VOC clinical isolates of B.1.1.7 (B), B.1.351 (C), and P.1 (D). Horizontal bars represent geometric mean titer and I bars represent 95% confidence intervals. Statistical comparisons were made using the Wilcoxon rank-sum test. LOD denotes limit of detection.