Observational study: prospective longitudinal cohort (Green)
The durability of immune memory after SARS-CoV-2 mRNA vaccination remains unclear. In this article the authors longitudinally profiled vaccine responses in SARS-CoV-2 naïve and recovered individuals for 6 months after vaccination. Antibodies declined from peak levels but remained detectable in most subjects at 6 months. They found mRNA vaccines generated functional memory B cells that increased from 3-6 months post-vaccination, with the majority of these cells cross-binding the Alpha, Beta, and Delta variants. mRNA vaccination further induced antigen-specific CD4+ and CD8+ T cells, and early CD4+ T cell responses correlated with long-term humoral immunity. Recall responses to vaccination in individuals with pre-existing immunity primarily increased antibody levels without substantially altering antibody decay rates. Together, these findings demonstrate robust cellular immune memory to SARS-CoV-2 and variants for at least 6 months after mRNA vaccination.
Goel, R. R. et al. Science 2021 Oct doi:10.1126/science.abm0829.