Antibody response after one and two jabs of the BNT162b2 vaccine in nursing home residents: The CONsort‐19 study

Background The humoral immune response following COVID‐19 vaccination in nursing home residents is poorly known. A longitudinal study compared levels of IgG antibodies against the spike protein (S‐RBD IgG) (S‐RDB protein IgG) after one and two BNT162b2/Pfizer jabs in residents with and without prior COVID‐19. Methods In 22 French nursing homes, COVID‐19 was diagnosed with real‐time reverse‐transcriptase polymerase chain reaction (RT‐PCR) for SARS‐CoV‐2. Blood S‐RDB‐protein IgG and nucleocapsid (N) IgG protein (N‐protein IgG) were measured 21–24 days after the first jab (1,004 residents) and 6 weeks after the second (820 residents). Results In 735 residents without prior COVID‐19, 41.7% remained seronegative for S‐RDB‐protein IgG after the first jab vs. 2.1% of the 270 RT‐PCR‐positive residents (p