The United States on Wednesday became the latest country to embrace the widespread use of coronavirus vaccine booster shots, citing new data that shows the vaccines’ effectiveness waning over time.

The Biden administration said it plans to make booster shots available to Americans starting the week of Sept. 20, pending reviews by federal health agencies. Officials said those who received the Pfizer-BioNTech and Moderna vaccines can receive a booster shot eight months after the date when they got their second vaccine dose. Officials said they are waiting for additional data before setting a plan for people who received the one-dose Johnson & Johnson vaccine.

Here’s what you need to know about booster shots and the United States’ plans.

What to know

  • Why is the U.S. planning to offer booster shots?
  • Who qualifies for a booster shot in the U.S., and when?
  • Why are booster shots recommended after eight months?
  • How will booster shots be distributed in the U.S.?
  • What other countries are offering boosters?
  • What about approval by health agencies?