Effect of recent SARS-CoV-2 infection on anti-spike protein immunoglobulin G II response after BNT162b2 vaccination

Abstract

Objectives

Our hospital experienced a SARS-CoV-2 outbreak 3 months before staff vaccination was initiated. This study compared antibody responses to the first and second doses of BNT162b2 mRNA vaccine among staff with and without prior infection.

Methods

Serum anti-spike (S) protein immunoglobulin (anti-S) IgG, IgM, and anti-nuclear (N) protein IgG, IgM were measured 1 week before the first dose (baseline). Serum anti-S IgG II levels were sequentially measured at the baseline, 3 weeks after the first dose (immediately prior to the second dose), and 3 weeks and 6 months after the second dose to assess neutralization activity.

Results

Ten of the 83 staff had evidence of prior SARS-CoV-2 infection. The baseline anti-S IgG, IgG II, anti-N IgM, and anti-N IgG levels were significantly higher in those with prior infection. Three weeks after the first dose, the mean anti-S IgG II level was significantly higher in the prior-infection group (406.94 ± 163.44 AU/mL) than that in the uninfected group (40.43 ± 50.16 AU/mL; p < 0.001). Three weeks after the second dose, the mean anti-S IgG II level was significantly lower than that after the first dose in the prior-infection group (240.28 ± 81.46 AU/mL; p = 0.007), and significantly higher in the uninfected group (341.45 ± 192.75 AU/mL; p < 0.001). Six months after the second dose, the mean anti-S IgG II levels did not differ significantly between groups.

Conclusions

A single dose of BNT162b2 vaccine is sufficient to induce a peak anti-S IgG II response in recently infected individuals.