A new study led by the researchers at Washington University School of Medicine at St. Louis and published in the journal Nature, suggests that months after recovering from mild cases of COVID-19 infection, people still have immune cells in their body pumping out antibodies against the SARS-CoV-2 virus. The study also found that such cells can last for a lifetime, pumping out antibodies all the time.
The study suggested that mild COVID cases leave people with lasting protection of antibodies and repeated infection is unlikely to occur. Last year, reports said that antibodies wane quickly after the infection, which was interpreted as immunity not lasting long. Antibodies go down after an acute infection, which is normal, however, they do not go down to zero, instead, they plateau.
During the study, antibody cells were found in people even after 11 months of infection, which is a long time.
After a viral infection, most of the antibody-producing immune cells die and there is a drop in the blood antibody levels. Though a small population of these antibody-producing immune cells, which are also called long-lived plasma cells migrate to the bone marrow and settle in. From there, the cells continue to secrete low levels of antibodies and help fight another encounter of the virus.