The immune system of people recovering from mild episodes of COVID-19 produces antibodies that can last only a few months, but that doesn’t mean protection is gone or an effective vaccine is not possible, according to new research.
Antibodies are proteins that white blood cells called B cells make to bind to the virus and help kill it. As an infection progresses, the immune system trains to attack its attack and produce more accurate antibodies.
Dr. Otto Yang and other scientists at the University of California, Los Angeles measured these most accurate antibodies among 30 infected people and four housemates suspected of having the disease.
Their average age was 43, and most had only mild symptoms.
The study, published Tuesday in the New England Journal of Medicine Researchers, found that the antibodies had a half-life of 73 days, meaning that half of them would disappear after that time.
An earlier report from China also suggested that the antibodies fade quickly.
The results “require caution regarding” antibody-based immunity passports, “herd immunity, and perhaps vaccine durability,” the California authors wrote in the study.
“Infection with this coronavirus does not necessarily generate lifelong immunity,” but antibodies are only part of the equation, said Dr. Buddy Creech, an infectious disease specialist at Vanderbilt University who was not involved in the study.
He said that other parts of the immune system also offer protection.
In addition to making antibodies, B cells develop a memory so they know how to do it again if necessary. The immune system remembers how to make new antibodies if necessary to mount an attack, Creech added.
“They would be quickly called to action when there is a new exposure to the virus. It’s like they’re dormant, just waiting, “he said, adding that other white blood cells, called T cells, are also better able to attack the virus when they see it again.
Alison Criss, an immunologist at the University of Virginia, said scientists need to find out if people remake antibodies and how they remake them if they are exposed to the insect again and if they protect themselves against another infection.
Vaccines, which cause the immune system to create antibodies, may provide longer lasting protection than natural infection because they use purified versions of what stimulates that response, he added.
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