Reduced BNT162b2 mRNA vaccine response in SARS-CoV-2-naive nursing home residents

Abstract

The SARS-CoV-2 pandemic impact on nursing home (NH) residents prompted their prioritization for early vaccination. To fill the data gap for vaccine immunogenicity in NH residents, we examined antibody levels after BNT162b2 mRNA vaccine to spike, receptor binding domain (RBD) and for virus neutralization in 149 NH residents and 111 health care worker controls. SARS-CoV-2-naive NH residents mount antibody responses with nearly 4-fold lower median neutralization titers and half the anti-spike level compared to SARS-CoV-2-naive healthcare workers. By contrast, SARS-CoV-2-recovered vaccinated NH residents had neutralization, anti-spike and anti-RBD titers similar to SARS-CoV-2-recovered vaccinated healthcare workers. NH residents' blunted antibody responses have important implications regarding the quality and durability of protection afforded by neoantigen vaccines. We urgently need better longitudinal evidence on vaccine effectiveness specific to NH resident populations to inform best practices for NH infection control measures, outbreak prevention and potential indication for a vaccine boost.

Figure 1.. Humoral immune assessment of BNT162b2 mRNA vaccine vaccination in NH residents

Post-vaccination anti-spike, anti-RBD and serum neutralization titers are shown. On the x axis, NH refers to NH residents and Control refers to the vaccinated younger healthcare workers or unvaccinated SARS-CoV-2 convalescent individuals. The dotted line in each panel is the median pre-immunization value in the SARS-CoV-2-naive subjects. Anti-Spike and Anti-RBD differences in geometric means were assessed using t-tests of log-transformed values. Given observed points at upper and lower limits of detection in neutralizing titer assay (12–8748), differences in distribution were assessed using the Wilcoxon rank-sum test. P-values were adjusted within assay (n = 6 tests per assay, Bonferroni method), and adjusted p-values < 0.001 are indicated with stars (***). We did not detect significant differences in any assay between the NH and Control subjects with prior SARS-CoV-2 or between the SARS-CoV-2-naive NH subjects and the convalescent unvaccinated controls.