New research suggests that the antibodies that the immune system makes to fight the new coronavirus may last only a few months in people with mild illnesses, but that doesn’t mean that protection has also disappeared or that it won’t be possible to develop an effective vaccine.
“Infection with this coronavirus does not necessarily create lifelong immunity,” but antibodies are only part of the story, said Dr. Buddy Creech, an infectious disease specialist at Vanderbilt University. He had no role in the job, published Tuesday in the New England Journal of Medicine.
The immune system remembers how to make new antibodies if necessary, and other parties can mount an attack, too, he said.
Antibodies are proteins that white blood cells called B cells make to bind to the virus and help kill it. The former are fairly raw, but as the infection progresses, the immune system trains to focus its attack and produce more accurate antibodies.
Dr. Otto Yang and others at the University of California, Los Angeles measured these most accurate antibodies in 30 patients diagnosed with COVID-19 and four housemates allegedly having the disease. Their average age was 43 years and most had mild symptoms.
The researchers found that the antibodies had a half-life of 73 days, meaning that half of them would disappear after so long. Corresponds to a previous report from China that also suggests that antibodies fade quickly.
The results “require caution regarding antibody-based ‘immunity passports’, herd immunity, and perhaps vaccine durability,” the California authors write.
That’s true, Creech said, but other parts of the immune system also help confer protection. In addition to making antibodies, B cells develop a memory so they know how to do it again if necessary.
“They would be quickly called into action when there is a new exposure to the virus. It is as if they are dormant, just waiting,” he said.
Other white blood cells called T cells may also attack the virus better the next time they see it, Creech said.
Although circulating antibodies may not last long, what we need to know is whether people redo the antibodies if they are re-exposed to the coronavirus and if they protect themselves against another infection, wrote Alison Criss, an immunologist at the University of Virginia, in an email . “We also need to know if there is a protective T cell response” that comes back.
Vaccines, which cause the immune system to produce antibodies, may provide longer-lasting protection than natural infection because they use purified versions of what stimulates that response, he noted.
Creech agreed.
“This should not discourage us from seeking a vaccine,” he said. “Antibodies are only part of the story.”
.
