Recent studies have suggested that to reach immunity, immunocompetent SARS-CoV-2 seropositive adults may only require 1 dose rather than 2 doses of an mRNA vaccine, however, these studies did not include older adults. Older adults living in nursing homes are at higher risk for severe COVID-19, and the immune response to the vaccine may differ from that of younger, healthier adults.
A study was conducted between March and June 2020, with residents from nursing homes in France. Six weeks after the end of an outbreak of COVID-19, all residents underwent blood testing for levels of IgG antibody against the SARS-CoV-2 nucleocapsid (N) protein. All residents from 6 nursing homes were offered a first vaccine dose in January 2021. Three weeks later, all residents underwent blood testing to quantitatively assess IgG antibody levels against the SARS-CoV-2 spike (S) protein and N protein.
This preliminary study suggests that a single dose of BNT162b2 vaccine may be sufficient to obtain a high level of S-protein IgG antibody in nursing home residents previously diagnosed with COVID-19 based on RT-PCR results. This is great news especially if we continue to struggle getting vaccines into arms! Stay well, mask up and stay tuned!