COVID-19 Booster Shots: What You Need to Know

COVID-19 booster shots are here. 

In the United States, Pfizer, Moderna, and Johnson & Johnson have each developed their own booster shots.

So far, the Food and Drug Administration (FDA) has authorized booster shots of Pfizer and Moderna five months after the second dose. Pfizer boosters have been approved for everyone ages 12 and older (as well as for certain immunocompromised children 5 through 11 years old), and Moderna for those 18 years and older. The FDA has also authorized a Johnson & Johnson booster for all adults (18+) who received a J&J vaccine as early as two months after their initial shot.

Eligible adults are able to choose any authorized COVID-19 booster—regardless of the vaccine type used for their initial vaccination (although Pfizer and Moderna vaccines are being recommended by the Centers for Disease Control and Prevention in most situations). Children and teens ages 5 to 17 who have completed Pfizer's primary series are only eligible for the Pfizer booster.

Because manufacturers have eagerly presented the FDA with clinical trial data for COVID-19 booster doses, there's a lot we already know about them. Moderna will administer half-size doses for its third shot, for example, and Johnson & Johnson's booster dose increases immunity nine-fold. 

Here, we asked experts what else we should know about boosters, from potential side effects to the intended rollout plan and timeframe. There's good news: After the bumpy road to COVID-19 vaccine distribution the first time around, the U.S. is more prepared than ever.