The US Food and Drug Administration has just authorized the use of booster shots for recipients of the Moderna and Johnson & Johnson vaccines. And those seeking out that extra dose can get one from a brand different from their initial shots.

In a new statement outlining new emergency use authorizations, the FDA says that individuals 65 years and older, as well as adults with high risk of severe COVID-19 or high exposure to the virus, can get an additional single booster dose of Moderna at least 6 months out from their first set of shots. The FDA also authorized that people 18 and older can receive a single booster dose of Johnson & Johnson two months after their initial immunization. Your booster does not have to match your initial vaccination series.

“The available data suggest waning immunity in some populations who are fully vaccinated,” said acting FDA Commissioner Janet Woodcock in a statement. “The availability of these authorized boosters is important for continued protection against COVID-19 disease.”

A single booster dose of the Pfizer-BioNTech vaccine has already been authorized for high risk adults at least 6 months out from their initial vaccination. The vast majority of the nearly 190 million Americans who are fully vaccinated against COVID-19 have received the Pfizer or Moderna options, while about 15 million have received the J&J vaccine.

[Related: The FDA officially approved Pfizer’s COVID-19 vaccine]

Despite a unanimous vote by a committee of FDA advisers to move forward with this booster authorization, a committee from the Centers for Disease Control and Prevention will still need to assess the data and make their own recommendations before official guidelines for Americans are changed. The committee of advisers is set to meet today, and once the CDC’s official guidance is issued, which could happen quickly after this advisory meeting, the rollout of boosters can begin. 

The FDA is supporting the mix and match approach after a study (funded by the National Institute of Health) found that using different vaccines is safe, and potentially more effective at bolstering the immune system than only matching shots. Flexibility with dosing by different brands will also ease logistical difficulties, getting much needed doses to people in places like nursing homes.

“From a public health perspective, there’s a clear need in some situations for some individuals to receive a different vaccine,” said Amanda Cohn, chief medical officer at the CDC’s National Center for Immunization and Respiratory Diseases, to The New York Times.

Mark Sawyer, committee member from Rady Children’s Hospital in San Diego, voiced his agreement with Cohn to NPR“I’m sold already, and that’s because I agree completely with Dr. Cohn’s comments that we need flexibility and improved access for everybody, which the flexibility of being able to mix and match will allow.”

Ofer Levy, a professor of pediatrics at Harvard Medical School, told NPR that, realistically, mixing and matching is likely already happening. “Many Americans are taking matters into their own hands,” he said. “I’m reading in the media that people are getting boosters or mixing different products through their primary care providers, or not revealing what they got before. In the real world, all these kinds of combinations of extra boosters are already happening.”