“Sterilizing immunity is not very frequent – it’s not ideal,” said Alessandro Sette, an immunologist at the La Jolla Institute of Immunology and co-leader of the study.
More often, people become infected a second time with a particular pathogen, and the immune system recognizes the invader and extinguishes the infection quickly. The coronovirus in particular is slow to do damage, giving the immune system plenty of time to kick into gear.
“It can be eliminated fast enough that not only are you not experiencing any symptoms, but you are not contagious,” Dr. Sette said.
Dr. Sete and his colleagues recruited 185 men and women, ages 19 to 81, who had recovered from Kovid-19. The majority had mild symptoms that did not require hospitalization; Most provided only one blood sample, but 38 provided multiple samples over several months.
The team tracked four components of the immune system: antibodies, B cells that make more antibodies than necessary; And two types of T cells that kill other infected cells. The idea was to create a picture of the immune response by looking at its components over time.
“If you look at just one, you can really miss the whole picture,” Dr. Said Cretty.
He and his colleagues found that antibodies were durable, with a slight decline six to eight months after infection, although there was a 200-fold difference in levels between participants. T cells showed only a slight, slow decay in the body, while B cells increased in number – an unexpected finding that researchers cannot quite explain.
Experts said such granular expansion is the first study of the immune response to the virus. “Certainly, we have no priests here,” Dr. Gommeran said. “We are learning, I think for the first time, about some of the dynamics of these populations through time.”