Significant Reduction in Vaccine-Induced Antibody Levels and Neutralization Activity Among Healthcare Workers and Nursing Home Residents 6 Months Following Coronavirus Disease 2019 BNT162b2 mRNA Vaccination

Abstract

Antibody decline occurred from 2 weeks to 6 months post-BNT162b2 mRNA vaccination in nursing home (NH) residents and healthcare workers. Antispike, receptor-binding domain, and neutralization levels dropped >81% irrespective of prior infection. Notably, 69% of infection-naive NH residents had neutralizing antibodies at or below the assay's limit of detection.

Keywords: COVID-19; antibody; long-term care; vaccine.

Figure 1.

Antibody levels 2 weeks and 6 months after BNT162b2 mRNA vaccination in healthcare workers (HCWs) and NH residents with and without severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection prior to vaccination. Post-vaccination anti-spike in BAU/mL (A), anti-RBD in AUs (B), and pNT50 (C) are shown. The lower limit of detection of the neutralization assay is 1:12. N for each assay and group of total participants depicted. Results are stratified by younger HCWs and NH residents. Prior infection refers to antibody levels at the given time points in individuals vaccinated after recovering from earlier SARS-CoV-2 infection, and infection naive refers to individuals vaccinated without prior SARS-CoV-2 infection. Geometric means were compared across groups at 2 weeks and 6 months using least-squares regression on log-transformed assay values. Post-hoc pairwise group differences at 6 months are presented here after Tukey adjustment for 4 group comparisons, with ∗∗ indicating P < .01 and ∗∗∗ indicating < 0.001. All 2-week to 6-month changes in all panels are significant, with paired t test P < .001 (not shown). Abbreviations: AU, arbitrary unit; BAU, binding arbitrary unit; NH, nursing home; pNT50, pseudovirus neutralization; RBD, receptor-binding domain.