Do the Covid vaccines provide long-lasting protection?

In the spring of 2022, officials authorized a second booster dose after the initial fall rollout. The same pattern followed in the spring of 2023 and the spring of 2024.

No other vaccines are given at such a high frequency, but experts say there’s no reason to believe that the vaccines — and in particular, the mRNA vaccines from Pfizer and Moderna — aren’t effective. ...

Despite the CDC recommending an additional shot, there’s no evidence that the mRNA vaccines aren’t working as expected, said Akiko Iwasaki, a professor of immunology at the Yale School of Medicine.

Rather, Iwasaki said, there may be something unique to this virus that is preventing people’s bodies from maintaining high levels of immunity.

A recent study from researchers at Emory University found that so-called hybrid immunity — when a person has been both vaccinated and infected with the coronavirus at some point — failed to significantly establish certain long-lasting cells that secrete antibodies. That wasn’t the case for people who had been vaccinated against the flu and tetanus, suggesting, Iwasaki said, that something different is happening with the virus. ...