Recovered patients less prone to reinfection, Covid variant: Study
People who recover from COVID-19 are protected against the novel coronavirus for at least six months, and likely much longer, according to a study which says the immune system evolves long after the infection and may block even mutant forms of the virus such as the South African variant.
The research, published in the journal Nature, noted that antibodies are produced by immune cells that keep evolving, apparently due to a continued exposure to remnants of the virus hidden in the gut tissue.
According to the scientists, including those from Rockefeller University in the US, the study provides the “strongest evidence yet” that the immune system “remembers” the virus and, remarkably, continues to improve the quality of antibodies even after the infection has waned. They suspect that when recovered patients next encounters the virus, the response would be both faster and more effective, preventing reinfection.
“This is really exciting news. The type of immune response we see here could potentially provide protection for quite some time, by enabling the body to mount a rapid and effective response to the virus upon re-exposure,” says Michel C. Nussenzweig, a co-author of the study from Rockefeller University.
While antibodies against the coronavirus linger in the blood plasma for several weeks or months, earlier studies have shown that their levels significantly drop with time. However, the researchers showed that instead of producing antibodies all the time, the immune system creates memory B cells that recognise the coronavirus, and quickly unleash a new round of antibodies when they encounter it a second time. Since the novel coronavirus replicates in the cells of the lungs, upper throat, and small intestine, they suspect that residual viral particles hiding within these tissues could be driving the evolution of memory B cells. According to the researchers, these antibodies were better able to latch on tightly to the virus, and could recognise mutated versions of it.