KNOXVILLE, Tenn. (WATE) — The U.S. government on Wednesday recommended all vaccinated Americans get a COVID-19 vaccine booster shot to shore up their protection against the virus. Many are wondering when they should get that shot. Here’s what we know.

U.S. health officials on Wednesday recommended that all Americans get booster shots 8 months after their second dose. Both COVID-19 vaccines made by Pfizer and Moderna require two doses for full vaccination.

The recommendation comes as officials encourage Americans to shore up their protection amid the surging delta variant and evidence that the vaccines’ effectiveness declines over time.

The plan, as outlined by the director of the Centers for Disease Control and Prevention and other top authorities, calls for an extra dose eight months after people get their second shot of the Pfizer or Moderna vaccine. The doses could begin the week of Sept. 20.

The following chart shows the months a booster shot is recommended 8 months after receiving the second dose of either the Pfizer or Moderna COVID-19 vaccine:


Booster shots are already available for those with compromised immune systems.

Last week, the Food and Drug Administration authorized the extra COVID-19 vaccine dose for the immunocompromised to better protect them as the delta variant continues to surge. Health authorities consider the extra dose part of the initial COVID-19 vaccine prescription for the immune-compromised.

NewsNation and The Associated Press contributed to this report.