from the study narrative:
“ A previous study found that patients older than 60 years had fewer memory B cells secreting total IgG and RBD-specific IgG than patients under 60 years old nine months after infection (8). In this study we observed that IgG concentrations declined from six to twelve months more substantially in subjects ≥60 years compared to younger age groups. Similar more rapid decline in neutralizing antibody concentrations was observed among elderly compared to younger subjects who were followed up to six months following vaccination (43). The results of our study support previous findings indicating that protection against infection mediated by neutralizing antibodies may be impaired against the variants of concern, especially after a mild disease”