Study: Vaccines provide enduring immune reaction

Vaccines made by PfizerBioNTech and Moderna set off a persistent immune reaction in the body that may protect against the coronavirus for years, scientists reported Monday.

The findings add to growing evidence that most people immunized with the mRNA vaccines may not need boosters, so long as the virus and its variants do not evolve much beyond their current forms — which is not guaranteed. People who recovered from COVID19 before being vaccinated may not need boosters even if the virus does make a significant transformation.

“It’s a good sign for how durable our immunity is from this vaccine,” said Ali Ellebedy, an immunologist at Washington University in St. Louis who led the study, which was published in the journal Nature.

Ellebedy and his colleagues reported last month that in people who survived COVID19, immune cells that recognize the virus lie quiescent in the bone marrow for at least eight months after infection. A study by another team indicated that socalled memory B cells continue to mature and strengthen for at least a year after infection.

Based on those findings, researchers suggested that immunity might last for years, possibly a lifetime, in people who were infected with the coronavirus and later vaccinated. But it was unclear whether vaccination alone might have a similarly longlasting effect.

The results suggest that a vast majority of vaccinated people will be protected over the long term — at least, against the existing coronavirus variants. But older adults, people with weak immune systems and those who take drugs that suppress immunity may need boosters.

Exactly how long the protection from mRNA vaccines will last is hard to predict. In the absence of variants that sidestep immunity, in theory immunity could last a lifetime, experts said. But the virus is clearly evolving.