Fourth mRNA vaccination increases cross-neutralizing antibody titers against SARS-CoV-2 variants, including BQ.1.1 and XBB, in a very elderly population
Description
CONCLUSION: The positivity rates for BQ.1.1 and XBB increased after 4th vaccination, although the titer value was lower than those of BA.5 and BA.2.75. Considering the rapid mutation of viruses and the efficacy of vaccines, it may be necessary to
