Don’t panic about waning coronavirus immunity: Your T cells go to bat when antibodies disappear

Some studies suggest that coronavirus antibodies can fade within weeks or months.
But that doesn’t mean our immunity disappears.
T cells identify and kill infected cells, and B cells create new antibodies.
Recent research showed that some people who were never exposed to the new coronavirus still have T cells that can identify and react to it.
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A handful of recent studies have painted a worrisome picture about immunity to the coronavirus: Early research suggests these protective proteins can fade within weeks or months.

But antibodies don’t tell the whole story.

Your protection against reinfection is wrapped up in the immune system’s multi-layered response to an invading virus. White blood cells have impressive powers of recollection that can help your body mount another attack against the coronavirus should it ever return: Memory T cells can identify and destroy infected cells, and inform B cells about how to craft new virus-targeting antibodies.

“These so-called memory cells are the main agents of long-term immunity,” two immunobiologists, Akiko Iwasaki and Ruslan Medzhitov, wrote in The New York Times on Friday. When it comes to antibodies, however, the level “in the blood peaks during an infection and drops after the infection has cleared, often within a few months,” they added.

A recent study, published July 15, examined 36 recovered coronavirus patients and found that all of them produced memory T cells that recognize and are specifically engineered to fight the virus. Those T cells will go to bat whether or not antibodies are still at detectable levels.

“The advantage of having really good T cells is even if the antibody levels have gone down, every time you get exposed again, the T cells will clone up and provide help really quickly, and those antibodies will be expanded again,” Dr. Richard Locksley, an infectious-disease expert, told Elemental.

‘There’s no evidence that immunity is fleeting’

Research is coalescing around the idea that people who catch COVID-19 develop robust T cell responses.

A study published Wednesday in the journal Nature found that among 18 German coronavirus patients, more than 80% developed virus-specific T cells.

Similarly, research published in May found that all members of a group of 20 coronavirus patients who’d gotten mild or moderate infections had helper T cells capable of recognizing the virus and responding accordingly. About 70% made killer T cells as well. A follow-up study also looked at 10 patients with severe COVID-19 cases that required hospitalization and found that all 10 produced helper T cells and 80% produced killer T cells.

“The data are suggestive that the average person makes a good immune response and may have immunity for some time,” Shane Crotty, a coauthor of that May study, previously told Business Insider.

Marm Kilpatrick, a disease ecologist at University of California Santa Cruz, previously told Business Insider that “there’s no evidence that immunity is fleeting and no rigorous estimates yet of how long it will last.”

He added that the limited …read more

Source:: Business Insider


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