New research suggests our immune systems remember the virus after recovering from COVID-19, and the antibodies we produce continue to improve after the infection has waned.
Researchers from Rockefeller University found that immune cells are able to produce more effective antibodies over time thanks to remnants of the virus hidden in gut tissue.
The findings suggest that when a person who has recovered from COVID-19 encounters the virus again, their immune response may be faster and stronger, preventing reinfection.
Our bodies respond to infection by producing antibodies, which linger in blood plasma for weeks or months, but the levels of antibodies drop over time. To save having to constantly produce antibodies, the immune system creates memory B cells that recognise the pathogen and can quickly generate new antibodies when they see it again.
The Rockefeller University researchers found that while antibodies against the SARS-Cov-2 virus had markedly decreased after six months but the memory B cells that produced these antibodies had not declined, and had even increased in some cases.
They also found something unexpected: the antibodies produced by the memory B cells were much more effective than the originals, because the cells had gone through multiple rounds of mutation after the infection was resolved.
Memory B cells often continue to evolve in chronic infections such as HIV but the researchers were surprised to see it with SARS-CoV-2, which was thought to leave the body after recovery.
They suspect the ongoing evolution is due to remnants of the virus hiding within tissues in the lungs, throat and small intestine. Traces of the virus’s genetic material have been found in some of the patients’ small intestine tissue.
The team plans to continue their research to learn more about how these viral remnants may drive the disease process and the immune response.