How long will COVID-19 resistance persist after recovery? :shot

Researchers are investigating the duration of antibody to coronavirus in people who have recovered from an infection.

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Simon Dawson / AP

Researchers are investigating the duration of antibody to coronavirus in people who have recovered from an infection.

Simon Dawson / AP

Since so many people rely on the vaccine to help end the coronavirus pandemic, any hint of bad news gets a lot of attention. This is the case for a series of studies investigating how long the antibody of a person infected with coronavirus persists.

Antibodies help prevent infection. Some diseases can prevent reinfection, but scientists can’t say if it’s the cause This applies to coronaviruses. Moreover, the remaining period of the antibody is not clear.

Three recent studies – China, UK And now in the United States-wondering how long people carry antibodies after infection. But reality may not be so disastrous Recent headlines suggest.

These latest papers are from the UCLA research group. They tracked 34 coronavir antibodies and found that average antibody levels dropped to half of where they started in about two and a half months.

“Of course, the big caveat is that this is just one snapshot in a relatively short period of time,” he said. Dr. Otto Yang of UCLA, “So I’m not sure if it will continue to have the same decline over time.”

Scientists have found that people with mild or no symptoms tend to have a weak immune response to the coronavirus. And Yang letter Published online New England Medical Journal, Focuses on people with mild illness.

“Most recovered without treatment at the hospital, so antibody titers [levels] “Yes, I have seen other people with very high antibody titers, which are 10 to 100 times higher.”

Research group based at Mount Ikern School of Medicine. Sinai in New York examined approximately 20,000 people with mild to moderate illness. A story that they feel more secure Unpublished research report.

They find that 90% of those people had an antibody response that lasted at least 3 months. And these antibodies neutralized the virus at least in the laboratory.

“It makes sense to assume that you have protection for a time frame of one to three years,” he says. Florian Crammer, One of the scientists in the study. “Of course, we are scientists. We need to prove it. That’s why everyone is cautious. But I think it’s a fairly fair assumption.”

Scientists have focused a lot on antibodies as markers of immunity, partly because they are easy to measure. Often antibodies tend to decline over time, in which case the immune system does not necessarily have to start over. Memories of past infections are stored in cells called memory B cells.

“These are cells that don’t actually make antibodies unless the virus comes back,” says Kramer. “But they react very quickly and make antibodies very quickly. So there are many weapons that the immune system has to deal with this virus.”

Yet another line of defense is a type of immune cell called a T cell.

“T cells are very important in the fight against viruses,” he says. Dr. Karinado At Stanford University. They can kill the virus. “So one thing we’re seeing [is] Will the T cell response decline as the antibody declines? “

Scientists developing some of the coronavirus vaccines have found that their product causes a strong T cell response. It contains Oxford University Vaccine, Is in an advanced stage of testing.

“We know from many other infectious diseases that the vaccine response can be much longer-lived than the natural infection response,” says Adrian Hill, lead investigator in the vaccine study.

That’s because people get strong doses with vaccines that stimulate a strong immune system.

“At COVID, we are confident that the vaccine is more durable than natural COVID infections,” says Hill.

And for now, those who are already infected with coronaviruses need to wait whether they remain immune and, if so, how long.

Immunity to four mildly circulating and mild cold coronaviruses does not last for years. Thus, the duration of an antibody response may depend at least in part on whether the infection caused a serious illness, and on the serious immune response.

You can contact NPR Science correspondent Richard Harris [email protected]..