The Biden administration announced Wednesday that most Americans who have received the coronavirus vaccines will need booster shots to combat waning immunity and the highly transmissible delta variant that is causing a surge in coronavirus cases. These booster shots are expected to be available beginning the week of Sept. 20.

This plan applies only to the Pfizer-BioNTech and Moderna vaccines, and Americans should get a booster shot eight months after receiving their second dose, the administration said. Guidance for people who received the one-dose Johnson & Johnson vaccine will come at a later date, officials said.

What does that mean for you? Health and science reporters Joel Achenbach and Carolyn Y. Johnson answered your questions. Both reporters have been covering the coronavirus for The Washington Post since January 2020 and focused most recently on the delta variant, vaccines, and the Centers for Disease Control and Prevention.

Here are some of the most common questions:

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Eliza Goren and Lizzy Raben, editors on The Post’s audience team, produced this Q&A.