You can now sign up for an omicron-specific COVID-19 booster

The updated COVID-19 vaccine, designed to target the omicron variant of the virus, is now starting to roll out at pharmacies nationwide. If you got your last dose of the vaccine at least two months ago, you’re likely eligible to sign up for another shot, though many doctors recommend waiting four to six months after immunization or infection to get the strongest response from your immune system.

Walgreens, CVS, and other pharmacies, are now offering appointments for updated vaccines from both Moderna and Pfizer-BioNTech. (Moderna’s shot is authorized for people 18 and older, and Pfizer’s is approved for those age 12 and older.) A Walgreens spokesperson said that the chain is adding appointments as booster doses become available, and may vary over the coming days as new stock arrives. Some appointments are available as soon as next week. Health clinics and hospitals will also be administering the new vaccine. A directory of sites is available at vaccines.gov.

The new vaccine, which the Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) approved this week, is bivalent, meaning that it targets both the original strain of the virus and the omicron subvariants that are dominant now. Because the effectiveness of the vaccine wanes over time, it can also help if you haven’t had a shot since last year. There isn’t yet real-world data about how much additional protection the updated version can provide, but it’s likely to at least temporarily boost your chances of avoiding infection—and more importantly—help avoid serious illness and hospitalization. Another surge of COVID-19 infections is likely this fall.

The updated vaccines didn’t go through the same rounds of testing as the original versions, but the process is comparable to the flu shot, which is updated each year without new tests and approvals. “I don’t have any concerns about safety,” Florian Krammer, a professor of vaccinology at the Icahn School of Medicine at Mount Sinai, told Fast Company recently. “In terms of efficacy and how well this works, we have to wait and see. But of course, having a more specific response to what is circulating should provide better protection against both symptomatic and asymptomatic disease.”