Mild COVID-19 cases may lead to lifelong antibody protection

ST. LOUIS, Mo. — It’s never a good day to know that you are infected with COVID-19, but a new study found that there is likely a silver backing to infect the virus. Patients with mild cases of coronavirus have antibodies that protect them from reinfection almost a year later, according to researchers. In fact, a team at the University of Washington School of Medicine in St. Louis believes that this protection from COVID is likely to last a lifetime.

Researchers explain the first report claiming that COVID antibodies disappear soon after the infection did not have all the facts. Their findings reveal that as patients become healthy, the number of immune cells that make antibodies decreases, but they are never completely eliminated.

“Last fall, it was reported that antibodies declined rapidly after being infected with the virus that causes COVID-19. Mainstream media I interpreted it as meaning that immunity did not last long, “said Dr. Ali Ellebedy, senior author and associate professor of pathology and immunology, medicine, and molecular microbiology. University release..

“But that’s a misunderstanding of the data. It’s normal for antibody levels to drop after an acute infection, but not to zero. They’re plateaus. Here, to people 11 months after the first symptoms. Antibody-producing cells have been found. These cells live and produce antibodies for the lives of the rest of us. This is strong evidence of long-lasting immunity. “

Ellebedy adds that COVID antibody production naturally rises while people deal with the virus. After the infection is cleared, these specialized immune cells (long-lived plasma cells) migrate to the bone marrow. Once they settle there, they begin to stir low levels of COVID antibodies to help protect against reinfection.

Scientists have discovered that immune cells that fight COVID continue to work “indefinitely.”

To find out how long the coronavirus immunity actually lasts, Ellebedy and the team began collecting both blood and bone marrow samples from those who recovered. From mild cases of COVID-19.. The researchers recruited 77 participants who volunteered to collect blood every one to three months after infection. Of these patients, only six needed hospitalization during their illness.

Eighteen participants also provided bone marrow samples 7-8 months after infection. Five returned four months later and provided a second bone marrow sample — almost a year after being infected with COVID-19. For comparison, the team also collected bone marrow from 11 people who had never experienced the coronavirus.

As a result, it became clear that COVID antibodies in the blood decreased rapidly within a few months after the virus was removed. However, these antibodies did not disappear completely and leveled off, and scientists detected them in patients 11 months later.

In addition, 15 bone marrow samples from coronavirus patients were included Antibody-producing cells It is intended for COVID-19. These cells were still present in the bone marrow of the five patients who returned to provide the second sample after four months. On the other hand, all 11 people who were not infected with COVID-19 did not have these antibody-producing cells in their bone marrow.

For COVID patients, researchers say there is no reason to think that these cells leave the human body.

“People with mild cases of COVID-19 get rid of the virus from their bodies 2-3 weeks after infection. Therefore, no virus causes a vigorous immune response. 7 or 11 months after infection“Ellebedy explains. “These cells are not dividing. They are stationary, they just sit in the bone marrow and secrete antibodies. They have been doing that ever since the infection was resolved, and they I will continue it indefinitely. “

Do people who are vaccinated or who deal with severe COVID infections receive the same protection?

Mild cases appear to provide lifelong protection, but the authors of the study said More serious symptoms The protection may be weakened.

“It can go in either direction,” admits Dr. Jackson Turner, the lead author of pathology and immunology instructors. “Inflammation plays a major role in severe COVID-19, and too much inflammation can lead to a defective immune response. But on the other hand, the reason people really get sick is often in the body. This is because there are many viruses in and around them, which can lead to a good immune response. Therefore, it is not clear. Reproduce the study in people with moderate to severe infections. You need to understand if you are likely to be protected from reinfection. “

The team is currently investigating whether people receiving the COVID-19 vaccine can enjoy the same long-term immunity.Currently, the CDC says anyone taking both doses of the Moderna or Pfizer vaccines. Fully protected It starts 2 weeks after the second shot. The same is true for people two weeks after receiving the Johnson & Johnson one-shot vaccine.

The study will be displayed in the journal Nature..