The Week (US)

Covid-19 immunity may last for years

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Most people who recover from Covid-19 should have immunity against the virus for at least a year—and possibly a lifetime if they were subsequent­ly vaccinated. That’s the conclusion of two new studies into how long protection against the disease is likely to last, reports The New York Times. For the first study, researcher­s took bone marrow samples from 19 people about seven months after they’d been infected. Fifteen had detectable memory B cells, which churn out antibodies when a known virus attacks the body. In the five participan­ts who agreed to provide stem cell samples four months later, the memory B cell numbers were largely unchanged. For the second study, scientists examined blood samples from 63 people who had recovered from Covid, 26 of who had received at least one dose of either the Pfizer or Moderna vaccine. They found that levels of so-called neutralizi­ng antibodies—essential for preventing reinfectio­n—remained unchanged between six and 12 months. The study also found that as memory B cells evolve, the antibodies they produce gain the ability to neutralize a wider group of Covid variants. In the unvaccinat­ed participan­ts, this neutralizi­ng activity diminished a year after infection. But among the vaccinated, it increased by about 50-fold. “People who were infected and get vaccinated really have a terrific response, a terrific set of antibodies,” says lead author Michel Nussenzwei­g, from Rockefelle­r University in New York. “I expect that they will last for a long time.”

 ??  ?? A memory B cell: Ready to fight the coronaviru­s
A memory B cell: Ready to fight the coronaviru­s

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