A closer look at the memory B cells revealed something surprising: these cells had gone through numerous rounds of mutation even after the infection resolved, and as a result the antibodies they produced were much more effective than the originals. Subsequent lab experiments showed this new set of antibodies were better able to latch on tightly to the virus and could recognize even mutated versions of it.

Rockefeller University. “Immune system mounts a lasting defense after recovery from COVID-19, researchers find.” ScienceDaily. http://www.sciencedaily.com/releases/2021/01/210121131909.htm (accessed January 26, 2021).

Journal Reference – Evolution of antibody immunity to SARS-CoV-2. Nature, 2021; DOI: 10.1038/s41586-021-03207-w