Bodies of people who have recovered from the novel coronavirus infection could be producing antibodies against the virus for months, according to a new study published in Nature.?
Also Read:?This Man Has Super Antibodies, COVID-19's Worst Nightmare
Researchers from the Washington University School of Medicine in St. Louis, believe that immune cells in such bodies could persist for a lifetime, pushing out antibodies for years to come.?
Ali Ellebedy, associate professor of pathology and immunology of medicine and of molecular biology explains the notion surrounding the number of antibodies going down, ¡°Last fall, there were reports that antibodies wane quickly after infection with the virus that causes COVID-19, and mainstream media interpreted that to mean that immunity was not long-lived. But that¡¯s a misinterpretation of the data.¡±
He added, ¡°It¡¯s normal for antibody levels to go down after acute infection, but they don¡¯t go down to zero; they plateau. Here, we found antibody-producing cells in people 11 months after first symptoms. These cells will live and produce antibodies for the rest of people¡¯s lives. That¡¯s strong evidence for long-lasting immunity.¡±
Researchers saw that in a viral infection, immune cells that were responsible for producing the antibodies rapidly grew in number and circulated in the bloodstream, skyrocketing the levels of antibodies. But, after the infection was eliminated, most of these cells disappeared, causing a drop in antibodies.?
However, researchers say that a small percentage of antibody-producing cells migrate to the bone marrow and settle there, while continuously releasing low levels of antibodies in the blood, protecting us from getting infected again.?
Also Read:?Three Months To Two Years: How Much Immunity Does Coronavirus Vaccine Provide
According to Ellebedy, the key to finding the answer to the question of long-lasting antibody protection lies in the bone marrow. He teamed up with Iskra Pusic, associate professor of medicine. They had enrolled 77 participants who were offering blood samples at three-month intervals from the first month after the initial infection. Most of its participants had a mild case with only six being hospitalised.?
Pusic helped in obtaining bone marrow samples from 18 of the participants seven to eight months after initial infections. Five came back after four months to give another bone marrow sample. For baseline, they got bone marrow samples from 11 individuals who never had COVID-19.?
Researchers in their results saw antibody levels in the blood drop as expected in the first few months and eventually levelled off, with some antibodies detectable even 11 months after the infection.?
Also Read:?Israel Develops Antibody That Can Neutralize COVID-19 In Body, Will Begin Mass Production Soon
On the other hand, 15 out of the 19 bone marrow samples from people who had COVID-19 contained antibody-producing cells specifically to take down the novel coronavirus. These cells were even found four months later in five individuals who offered a second bone marrow sample. This was completely absent in the 11 individuals who never had COVID-19.
¡°People with mild cases of COVID-19 clear the virus from their bodies two to three weeks after infection, so there would be no virus driving an active immune response seven or 11 months after infection,¡± Ellebedy said. ¡°These cells are not dividing. They are quiescent, just sitting in the bone marrow and secreting antibodies. They have been doing that ever since the infection resolved, and they will continue doing that indefinitely.¡±