“Sterile immunity rarely occurs,” said Alessandro Sette, an immunologist at the La Jolla Institute of Immunology and co-leader of the study. This is not common.
More often, people are infected a second time with a specific pathogen, and the immune system recognizes the invader and quickly quells the infection. Coronavirus in particular is slow to do harm, so you have plenty of time for your immune system to work.
Dr. Sette said, “Not only do you not experience symptoms, it can be terminated so quickly that you don’t get infected.”
Dr. Sette and his colleagues recruited 185 men and women who recovered from Covid-19 between the ages of 19 and 81. The majority had mild symptoms that did not require hospitalization. Most provided only one blood sample, but 38 provided multiple samples over several months.
Researchers tracked four components of the immune system. Antibodies, B cells that make more antibodies as needed; And two types of T cells that kill other infected cells. The idea was to create a picture of the immune response over time by looking at its components.
Dr. Crotty said, “You can miss the whole picture by looking at one.”
He and his colleagues found that antibodies were durable and decreased moderately between 6 and 8 months after infection. However, the figures differed 200 times between the participants. T cells showed only a slight slow decline in the body, and B cells increased numerically. Researchers cannot explain it as an unexpected discovery.
The study is the first to chart the immune response to the virus in this detail, experts said. Dr. Gommerman said, “Certainly there is no dictionary here. “We are learning for the first time about the dynamics of these populations over time.”