All three COVID-19 vaccines authorized for use in the United States are now approved for “mix and match” booster doses following an announcement from the Food and Drug Administration, or FDA.

The FDA expanded the emergency use authorizations for COVID-19 vaccines Oct. 20 to include a single booster dose of the Moderna and Johnson & Johnson vaccines for eligible groups and a “mix and match” approach to the boosters for recipients of all three vaccines. The announcement came one month after the FDA authorized Pfizer-BioNTech booster shots for eligible individuals in September.

“As of today, it’s a new world in terms of boosters and mix and matching,” said John Swartzberg, campus professor emeritus of infectious disease and vaccinology at the School of Public Health.

The approval authorizes the use of a booster dose of the Moderna vaccine six months after full vaccination in individuals 65 years of age or older and those at high risk, including individuals who are immunocompromised or may have high exposure to the virus through their occupation. The approval also authorizes the use of a booster dose of the Johnson & Johnson vaccine two months after full vaccination in individuals 18 years of age or older, according to the FDA press release.

The “mix and match” authorization also allows the use of the Moderna, Johnson & Johnson and Pfizer-BioNTech vaccines in eligible individuals after full vaccination using a different vaccine, according to the press release.

Swartzberg and Lee Riley, chair of the campus division of infectious diseases and vaccinology, both noted the difficulty in communicating booster shot eligibility.

“People are still confused,” Riley said.

Swartzberg added that the messages surrounding booster shots were “nuanced” and it was left up to the public to decide whether they were at high risk.

Citing the availability of the vaccine in the Berkeley community, University Health Services, or UHS, “will not be providing COVID vaccine boosters broadly to the campus community,” according to UHS spokesperson Tami Cate.

With some of its vaccine supply about to expire, UHS will be offering a vaccine clinic Oct. 29 at Pauley Ballroom. UHS does not anticipate that it will be receiving enough vaccines to continue holding large-scale vaccination clinics, however.

The Oct. 29 clinic will be open to faculty, staff and students who meet eligibility criteria, including international students who have received vaccines approved by the World Health Organization aside from the Pfizer-BioNTech, Moderna and Johnson & Johnson vaccines, according to Cate.

The available evidence shows that mixing vaccines can provide a stronger immune response, especially to recipients of the single-dose Johnson & Johnson vaccine, Swartzberg said. He added that the mixing and matching approach to booster vaccines also “makes the logistics a lot easier.”

“I’m certainly hoping that large parts of the population avail themselves of booster doses,” said Arthur Reingold, professor of epidemiology at the School of Public Health, though he added that “it’s not a substitute for the unvaccinated to get vaccinated in the first place.”