Research has found that people who have had mild cases of COVID-19 retain immune cells that pump out antibodies that protect against the COVID-19 causing virus months after recovering. These immune cells could continue to persist for life, making antibodies all of the time. The study results indicate that mild cases of COVID-19 provide long-lasting antibody protection and that recurring bouts of illness are unlikely to be common.1✅ JOURNAL REFERENCE
DOI: 10.1038/s41586-021-03647-4
There were reports in the fall of 2020 that antibodies would diminish rapidly following infection with the virus that leads to COVID-19, and it was construed by mainstream media to suggest that immunity wasn’t long-lived, which was actually a misinterpretation of the data. It’s quite common for levels of antibodies to drop following an acute infection, they however plateau as opposed to dropping to zero. In this study, cells that produce antibodies were found in individuals 11 months following their first symptoms. These immune cells will continue producing antibodies for the remainder of their lives, and is solid proof for long-lasting immunity.
Immune cells that produce antibodies quickly circulate and multiply in the blood during a viral infection, which drives levels of antibodies sky-high. Most of these immune cells die off as soon as the infection is over, and antibody levels decline. A small amount of cells that produce antibodies, known as long-lived plasma cells, then migrate to the bone marrow where they remain. Here they are constantly secreting low levels of antibodies in to the blood to help in protecting against another attack from the virus. The answer to finding out if COVID-19 results in enduring antibody protection thus lies in the bone marrow.
The researchers obtained bone marrow from 18 individuals 7 or 8 months after their initial mild cases of COVID-19infections to determine if they have long-lived plasma cells which produce antibodies that are specifically targeted to the virus that leads to COVID-19 known as SARS-CoV-2. Five of the individuals returned 4 months later and gave a 2nd sample of bone marrow. Bone marrow was also acquired from 11 individuals who had never been infected with COVID-19 for comparison.
Needlessly to say, antibody blood levels of the COVID-19 individuals dropped rapidly in the 1st few months following infection and then typically plateaued, with a quantity of antibodies detected 11 months following infection. Additionally, 15 of the 19 bone marrow samples taken from individuals who had been infected with COVID-19 had antibody-producing cells that are specifically targeting the virus that results in COVID-19 infection. These antibody producing cells could still be detected 4 months afterwards in the 5 people who returned to give a 2nd bone-marrow sample. The antibody-producing cells were not detected in the bone marrow of any of the 11 individuals who didn’t have COVID-19.
The virus is cleared from the bodies of individuals suffering from mild cases of COVID-19 two to three weeks following infection, and there wouldn’t be any virus generating an active immune response 7 or 11 months following infection. These cells are quiescent, they just sit in the bone marrow and secrete antibodies. They’ve been doing that from the time the infection went away, and they’ll continue secreting antibodies indefinitely. The researchers theorized that individuals who had been infected and didn’t have symptoms may also have long-lasting immunity.
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