Even mild Covid-19 cases confer ‘durable immunity,’ new studies find.
Scientists who have been monitoring immune responses to the coronavirus for months are now starting to see encouraging signs of strong, lasting immunity, even in people that developed only mild symptoms of Covid-19, a flurry of new studies has found.
Disease-fighting antibodies, as well as immune cells called B cells and T cells capable of recognizing the virus, appear to persist months after infections have resolved — an encouraging echo of the body’s robust immune response to other viruses.
“This is exactly what you would hope for,” said Marion Pepper, an immunologist at the University of Washington and an author on one of the new studies, which is currently under review at the journal Nature. “All the pieces are there to have a totally protective immune response.”
“This is very promising,” said Smita Iyer, an immunologist at the University of California, Davis, who is studying immune responses to the coronavirus in rhesus macaques and was not involved in these papers. “This calls for some optimism about herd immunity, and potentially a vaccine.”
Research on the coronavirus is proceeding so quickly, and in such volume, that the traditional review process often cannot keep pace. For the studies discussed here — as with un-peer-reviewed studies in general — The Times arranged for several experts to read and evaluate them.
Although researchers cannot forecast how long these immune responses will last, many experts consider the data a welcome indication that the body has a good chance of fending off the coronavirus if exposed to it again.
“Things are really working as they’re supposed to,” said Deepta Bhattacharya, an immunologist at the University of Arizona and an author on one of the new studies, which has not yet been peer reviewed.
Protection against reinfection cannot be fully confirmed until there is proof that most people who encounter the virus a second time are actually able to keep it at bay, Dr. Pepper said. But the findings could help quell recent concerns over the virus’s ability to dupe the immune system into amnesia, leaving people vulnerable to repeat bouts of disease.