Hope for a future without fear of COVID-19 comes down to circulating antibodies and memory B cells, reports Medical Xpress. Unlike circulating antibodies, which peak soon after vaccination or infection only to fade a few months later, memory B cells can stick around to prevent severe disease for decades. And they evolve over time, learning to produce successively more potent “memory antibodies” that are better at neutralizing the virus and more capable of adapting to variants. Vaccination produces greater amounts of circulating antibodies than natural infection. But a new study suggests that not all memory B cells are created equal. While vaccination gives rise to memory B cells that evolve over a few weeks, natural infection births memory B cells that continue to evolve over several months, producing highly potent antibodies adept at eliminating even viral variants. The findings highlight an advantage bestowed by natural infection rather than vaccination, but the authors caution that the benefits of stronger memory B cells do not outweigh the risk of disability and death from COVID-19. When any virus enters the body, immune cells immediately churn out hordes of circulating antibodies. Foot soldiers of the immune system, these antibodies burn bright but decay at variable rates depending on the vaccine or infection – they may protect us for months or years but then dwindle in number, allowing possible reinfection. The immune system has a backup plan: an elite cadre of memory B cells that outlive circulating antibodies to produce so-called memory antibodies that provide long-term protection. Studies suggest that memory B cells for smallpox last at least 60 years after vaccination; those for Spanish flu, nearly a century. And while memory B cells don’t necessarily block reinfection, they can prevent severe disease. Recent studies have suggested that within five months of receiving a vaccine or recovering from a natural infection, some of us no longer retain sufficient circulating antibodies to keep the novel coronavirus at bay, but our memory B cells stand vigilant. Until now, however, scientists did not know whether the vaccines could be expected to provide the sort of robust memory B cell response seen after natural infection.
https://medicalxpress.com/news/2021-10-natural-infection-vaccination-differences-covid.html
