On Friday (Nov. 19), the U.S. Food and Drug Administration (FDA) authorized COVID-19 booster doses for all adults 18 years of age or older, who previously received two doses of Pfizer-BioNTech or Moderna vaccines.

If a Centers for Disease Control and Prevention (CDC) advisory committee that meets today then recommends the shots for all adults, then millions more people will be eligible to get the shots prior to the busy holiday season.

"The FDA has determined that the currently available data support expanding the eligibility of a single booster dose of the Moderna and Pfizer-BioNTech COVID-19 vaccines to individuals 18 years of age and older," Dr. Peter Marks, the director of the FDA’s Center for Biologics Evaluation and Research, said in a statement.

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What's more, expanding eligibility will "help to eliminate confusion about who may receive a booster dose and ensure booster doses are available to all who may need one," Marks added.

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Booster doses have already been authorized for a subset of U.S. adults: those who are immunocompromised, who are 65 years of age or older or younger adults with underlying conditions or who are at high-risk due to where they live or work. Last week, California and Colorado were the first states to expand booster shot eligibility to all adults, Live Science previously reported.

The decision to expand booster doses for all adults is based on data from clinical studies that showed a booster dose restored vaccine efficacy and reduced severe disease.

Originally published on Live Science.