Antibodies are proteins produced by your immune system that fight viruses and other microbes. The cells that produce these antibodies can persist for years after an infection, and generating these cells is the basis for vaccination.

It has been clear for some time that Covid-19 patients generated a strong antibody response – at least initially – and that reinfection with the virus is extremely rare. It has also been clear for some time that SARS-CoV-2 (the virus that causes Covid-19) mutates its DNA very infrequently. These clues indicate that immunity to Covid-19 should be durable after recovery or vaccination. Here researchers from Rockefeller University found that not only did the antibody response in recovered Covid-19 patients not degrade over time, but that the quality of the antibodies produced was actually enhanced months after recovery. This is great news, but why would the antibody response continue to evolve, even after recovery? One possible explanation is that the virus is hiding out in the body and continuing to stimulate the immune system. The researchers subsequently found a small reservoir of the virus hiding in the patients’ small intestine. Importantly, these patients had no symptoms and no ability to transmit the virus, indicating that the immune system had done its job. Covid-19 Antibody Response