Indeed, Moderna officials have said they’re seeking broader authorization so that public-health authorities at the federal Centers for Disease Control and Prevention, as well as doctors and healthcare providers, could determine the appropriate use of a second booster for people at higher risk of infection or serious illness.

It’s likely that people over 65 and people who are immunocompromised will need second booster shots as the BA.2 variant spreads to the U.S., Amiji says. For younger people, though, whether a second booster—or an annual shot like the flu shot—is necessary will depend upon how much the protection from the first three shots wanes over time.

As COVID-19 becomes endemic, public-health and healthcare officials will need to continue to monitor the severity of new viral strains, Amiji says, but it’s likely that recommendations for further vaccination will come on a case-by-case basis, rather than the mass vaccination and booster campaigns that have defined the pandemic so far.

“I’m hopeful that when the fall comes, not everyone will need to be vaccinated again,” he says. “You’ll be able to decide whether it’s right for you.”