The U.S. Food and Drug Administration (FDA) on Sept. 22 gave emergency use for a booster shot of the Pfizer vaccine for Americans 65 and older. The company submitted data to the FDA earlier this summer to support booster shots of its COVID-19 vaccine.“This pandemic is dynamic and evolving, with new data about vaccine safety and effectiveness becoming available every day. As we learn more about the safety and effectiveness of COVID-19 vaccines, including the use of a booster dose, we will continue to evaluate the rapidly changing science and keep the public informed,” said Acting FDA Commissioner Janet Woodcock in a statement.However, the U.S. Centers for Disease Control and Prevention (CDC) also gets to weigh in. It will consider how to roll out booster shots of the Pfizer vaccine. Booster shots should be available within days, according to a USA Today report.Here’s what you need to know.For more TPG news delivered each morning to your inbox, sign up for our daily newsletter.Who would be eligible for a COVID-19 booster shot?The FDA is supporting approving COVID-19 booster shots for Americans 65 and older. It also said that employees in certain high-risk occupations, such as health care workers, teachers and grocery workers, would be eligible to receive a booster shot.Additionally, the agency also said Americans 18 and up who were at high risk of severe risk for contracting COVID-19 would be eligible to receive a booster shot. The FDA said it considered “the totality of the available scientific evidence” in reaching its decision.Which vaccines are available for a COVID-19 booster shot?(Photo by Chandan Khanna/AFP via Getty Images)So far, just the Pfizer vaccine has been recommended for a COVID-19 booster shot.“Today’s authorization applies only to the Pfizer-BioNTech COVID-19 vaccine,” the FDA statement said.Sign up for our daily newsletterEmail addressSign upI would like to subscribe to The Points Guy newsletters and special email promotions. The Points Guy will not share or sell your email. See privacy policy.According to the Associated Press, the U.S. will decide whether people who received another COVID-19 shot, such as Moderna or Johnson & Johnson, will need a booster shot “at a later date.” The FDA is not recommending people who got another vaccine to get a Pfizer booster vaccine.What about children?The FDA authorization only applies to Americans 18 and older. Currently, the Pfizer vaccine is the only one available for children as young as 12. The Moderna and Johnson & Johnson vaccines are only available to people 18 and older at this time.Pfizer recently said its vaccine was safe for children 5 to 11 and that it showed “robust” antibody responses against the COVID-19 disease.Why is a third dose being recommended?With the delta variant’s spread – and how transmissible it is – health experts appear to be taking a more urgent approach to getting booster shots into certain peoples’ arms. These people include older Americans and those with compromised immune systems.But getting to this point has been a battle, and not everyone has agreed on whether Americans need booster shots. Initially, several health agencies in the U.S. said this summer that people didn’t need a booster shot. And the World Health Organization has repeatedly warned against booster shots to allow lower-income countries to vaccinate their citizens.“What WHO is arguing is that booster doses in the general population, who had wide access to vaccines, who have already been vaccinated, is not the best bet right now,” said Dr. Mike Ryan, director of the WHO’s health emergencies program, according to CNBC.