(The Hill) — Last week, the Centers for Disease Control and Prevention expanded the eligibility for COVID-19 booster shots in the U.S. According to reporting from Business Insider, many more people are now allowed to get the third dose, even if they don’t know it yet. 

Under the CDC’s new guidelines, more people who received the Pfizer or Moderna vaccine are now eligible for the booster shot. For those who received either vaccines six months ago and are 65 years or older, the booster shot is now recommended.

Pfizer and Moderna vaccines, both of which require two doses, are about 95% effective against symptomatic COVID-19. 

The Johnson & Johnson vaccine requires only one dose and is said to be 66% effective against COVID-19.

In addition to the 65-years-and-older population, the booster shot is now available for those who are 18 years or older living in long-term care settings, have underlying medical conditions, and work or live in high-risk settings. 

Booster shots are available to those who received Johnson & Johnson’s vaccine at least two months ago. Nearly 15 million people have received the Johnson & Johnson vaccine, according to the CDC.

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The Food and Drugs Administration has also approved mixing vaccinations, which means Johnson & Johnson users can get a Pfizer or Moderna booster and vice versa, according to The Houston Chronicle

In the U.S., more than 108 million people were vaccinated six months ago and more likely in need of a booster shot.