mRNA vaccines induce durable immune memory to SARS-CoV-2 and variants of concern

The durability of immune memory after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) messenger RNA (mRNA) vaccination remains unclear. In this study, we longitudinally profiled vaccine responses in SARS-CoV-2-naive and -recovered individuals for 6 months after vaccination. Antibodies declined from peak levels but remained detectable in most subjects at 6 months. By contrast, mRNA vaccines generated functional memory B cells that increased from 3 to 6 months postvaccination, 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 preexisting immunity primarily increased antibody levels without substantially altering antibody decay rates. Together, these findings demonstrate robust cellular immune memory to SARS-CoV-2 and its variants for at least 6 months after mRNA vaccination.

Automated summary

This study found that immune memory to SARS-CoV-2 and its variants remains robust for at least 6 months after mRNA vaccination, with antibodies declining but still detectable in most individuals. mRNA vaccines also induced functional memory B cells and antigen-specific T cells, with recall responses primarily increasing antibody levels in individuals with preexisting immunity.