Centers for Disease Control and Prevention Director Rochelle Walensky approved coronavirus vaccine boosters for all adults on Friday, as federal health officials try to prop up vaccine efficacy as winter approaches and millions of Americans plan to travel during the holiday season. Earlier in the day, the Federal Food and Drug Administration authorized Moderna and Pfizer booster shots. A panel of advisors for the Centers for Disease Control then endorsed the FDA’s position to Walensky.

Previously, only certain groups were eligible for a third dose of either shot — including individuals 65 and older, anyone 18 and over with underlying medical conditions or living in a long-term care setting, and anyone 18 and older working in a high-risk setting. In October, boosters of both Moderna and Pfizer became available to any adult that had received an original Johnson & Johnson vaccine. While the FDA’s approval only came on Friday, several states have already begun boosting all adults, citing demand for increased protection ahead of the holidays and fears around breakthrough cases.

Shortly after the FDA’s ruling on Friday, Maryland Gov. Larry Hogan authorized the expansion of booster eligibility to all adults. D.C. Mayor Muriel Bowser on Friday encouraged adults to get boosters. Dr. Danny Avula, the state vaccination liaison for Virginia, did the same.

“All vaccines’ effectiveness wanes over time, and the data show a tangible benefit to people when they receive a vaccine booster,” Avula said in a statement. 

With eligibility now including hundreds of thousands of D.C.-area residents, here’s what you need to know about getting your booster in the region:

I got J&J, but I want a Moderna or Pfizer booster. Is that cool? 

Yes. The CDC’s latest recommendation allows for “mixing and matching” booster doses, and the agency is not going to issue a guidance on which vaccine an individual should get. According to their website: “Some people may have a preference for the vaccine type that they originally received, and others may prefer to get a different booster.” If you received an initial two doses of Moderna, you can get a Pfizer booster, and vice versa.

Where can I get it locally?

In D.C., residents can get a booster at more than 100 locations — including vaccine clinics, pharmacies, or health providers.

In Arlington County, boosters will be administered by appointment only. In Alexandria, residents can book booster appointments online, and Fairfax County is now offering Moderna boosters in addition to Pfizer shots. Residents can either book an appointment online or visit one of Fairfax’s walk-up sites.

Both Prince George’s County and Montgomery County are offering boosters at several county-run clinics and regional providers. You can use Maryland’s vaccine locator to set up an appointment, or consult the health department website to locate a mobile clinic. Montgomery County has added two additional vaccination sites to aid the booster rollout.

What do I need to bring? 

Yourself, your vaccination card, and it’s best to bring some form of identification along as well.

What about immunocompromised people?

In August, the CDC recommended third shots of either Moderna or Pfizer for individuals with compromised immune systems, shortly after the Food and Drug Administration amended both Moderna’s and Pfizer’s emergency use authorizations to allow for an additional dose.

The CDC has a list of conditions that fall under what is considered “moderate to severely immunocompromised,” but recommends that individuals consult their doctor before getting a third dose. Because first or second doses may not have sparked an immune response, a third shot of Pfizer or Moderna for an immunocompromised person is considered a supplemental dose, not a booster.

When can I get one?

The Pfizer and Moderna boosters can be administered to any individual who completed their vaccination series at least six months ago (i.e. received their second shot of Pfizer or Moderna at least six months ago, or received their Johnson & Johnson shot two months ago).

For months ,the scientific community has been divided on who should be getting a booster. The World Health Organization has criticized the push for third doses in the U.S. while some countries struggle to get first shots in arms, as some U.S. officials, including President Joe Biden, have pressed for wide ranging booster administration for months.

Two doses of a vaccine still provide strong protection against serious illness and death, but recent studies have found that the efficacy of both Pfizer and Moderna vaccines wanes over time, prompting the expansion ahead of the holiday season, and as cases tick up nationally. 

This story has been updated to include the most recent booster information.