Recovered from COVID-19: Do Antibodies Last a Lifetime?

Many people infected with SARS-CoV-2 are likely to produce antibodies against the virus for most of their lives.. Researchers have identified long-lasting antibody-producing cells in the bone marrow of people who have recovered from COVID-19. Serum anti-SARS-CoV-2 antibody levels have been reported to decline rapidly in the first few months after infection, which is worrying given the possibility that Long-lasting BMPCs (Bone Marrow Plasma Cells) are not generated and immunity to SARS-CoV-2 is short-lived.

However, in a study published by the specialized journal Nature conducted by a team led by Jackson Turner, Department of Pathology and Immunology, University of Washington School of Medicine, USA, in recovering people with mild SARS-CoV-2 infections, Serum levels of anti-SARS-CoV-2 spikeprotein (S) antibodies decreased rapidly during the first 4 months after infection.

In the initial phase of the study, samples showed this reduction. While between four and eleven months after infection, this reduction slowed down.

However, The researchers also took bone marrow samples from previously infected patients to measure the presence of bone marrow plasma cells., which are important in protecting antibodies and developing long-term protection against the virus.

In the samples, Researchers have found long-lived plasma cells in the bone marrow that are said to produce antibodies against COVID-19. Unlike the decline in other antibodies they observed, BMPC levels were stable for 7 to 11 months after infection. “We are looking for the source of these antibodies which are produced by cells that live in our bone marrow,” said Ali Ellebedy, associate professor at the Washington University School of Medicine in St. Louis, participating in the study. .

The study provides evidence that the immunity induced by SARS-CoV-2 infection would be remarkably long-lasting. In addition to the good news, “the implications are that the vaccines will have the same effect,” says Menno van Zelm, an immunologist at Monash University in Melbourne, Australia.

Antibodies, proteins that can recognize and help inactivate viral particles, are a key immune defense. After a new infection, short-lived cells called plasmablasts are an early source of antibodies. But these cells regress soon after a virus is cleared from the body, and other more durable cells make antibodies: Memory B cells patrol the blood for reinfection, while BMPCs hide in bones, producing antibodies for decades.

“A plasma cell is our life story, in terms of the pathogens to which we have been exposed”, explains Ali Ellebedy.

Researchers speculated that infection with SARS-CoV-2 would trigger the development of BMPC, like almost all viral infections, but there were signs that severe COVID-19 could disrupt cell formation. Some of the early studies on COVID-19 immunity also raised concerns, when they found antibody levels plummeted shortly after recovery.

To identify the source of the antibodies, the Monash University team collected memory and bone marrow B cells from a subset of participants. Seven months after symptoms developed, most of these participants still had memory B cells that recognized SARS-CoV-2. In 15 of 18 bone marrow samples, scientists found ultra-low but detectable populations of BMPCs whose formation was triggered by coronavirus infections in individuals seven to eight months earlier. The levels of these cells were stable in the five people who donated another bone marrow sample several months later.

“This is a very important observation, given the claims of declining antibodies against SARS-CoV-2,” said Rafi Ahmed, an immunologist at Emory University in Atlanta, Georgia, whose team co- discovered the cells at the end of May. “What’s not clear is what long-term antibody levels will look like and whether they offer protection, Ahmed says. We are at the start of the game. We do not look at five years, ten years after infection ”.

This team saw the first signs that Pfizer’s mRNA vaccine should trigger production of the same cells. Corn Persistent antibody production, whether caused by vaccination or infection, does not guarantee lasting immunity to COVID-19. “The ability of some emerging variants of SARS-CoV-2 to attenuate the protective effects of antibodies means that additional vaccinations may be needed to restore levels,” concludes Ellebedy. My presumption is that we will need a reinforcement ”.

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