Spike Antibody Levels of Nursing Home Residents With or Without Prior COVID-19 3 Weeks After a Single BNT162b2 Vaccine Dose

Abstract

This study compares IgG antibody levels after a single dose of the BNT162b2 (Pfizer-BioNTech) vaccine in nursing home residents with vs without prior COVID-19.

Figure.. Levels of IgG Antibody Against the SARS-CoV-2 Spike (S) Protein After a Single Dose of Vaccine in Nursing Home Residents

Between March and June 2020, nursing home residents facing a COVID-19 outbreak had repeated reverse transcriptase–polymerase chain reaction (RT-PCR) testing. They underwent testing for IgG antibodies against the SARS-CoV-2 nucleocapsid (N) protein 6 weeks after the end of the outbreak. There were 60 residents who had no prior SARS-CoV-2 infection (repeated negative RT-PCR result for COVID-19 and were seronegative for N-protein IgG after the outbreak) and 42 had SARS-CoV-2 infection (COVID-19). Of the 42 residents who had SARS-CoV-2 infection, 36 had a positive RT-PCR result and were seropositive for N-protein IgG, 5 had repeated negative RT-PCR results but were seropositive for N-protein IgG after the outbreak, and 1 had a positive RT-PCR result during the outbreak but was seronegative for N-protein IgG after the outbreak. Levels of S-protein IgG that were measured 3 weeks after a single BNT162b2 vaccine dose was administered in January 2021 (1 dot per resident) were significantly lower in residents without prior COVID-19 vs those with prior COVID-19 (P < .001). Among residents with prior COVID-19, levels of S-protein IgG were not statistically significantly different between residents with a positive RT-PCR result for COVID-19 and were either seropositive or seronegative for N-protein IgG compared with those with a negative RT-PCR result for COVID-19 and were seropositive for N-protein IgG (P = .25). The horizontal blue and orange lines represent median values for S-protein IgG.