All adults in the United States are now eligible to receive a booster dose of Pfizer (PFE  )-BioNTech's (BNTX  ) and Moderna's (MRNA  ) COVID vaccines, after the U.S. Centers for Disease Control and Prevention (CDC) signed off on the shots for the general public on Friday.

CDC Director Dr. Rochelle Walensky authorized the booster shots soon after the agency's independent vaccine advisory panel--the Advisory Committee on Immunization Practices--unanimously endorses expanded eligibility beyond the more vulnerable to severe disease to every adult at least six months after they received their second dose.

"After critical scientific evaluation, today's unanimous decision carefully considered the current state of the pandemic, the latest vaccine effectiveness data over time, and review of safety data from people who have already received a COVID-19 primary vaccine series and booster," said Walensky in a press statement. "Booster shots have demonstrated the ability to safely increase people's protection against infection and severe outcomes and are an important public health tool to strengthen our defense against the virus as we enter the winter holiday."

"Based on the compelling evidence, all adults over 18 should now have equitable access to a COVID-19 booster dose," she added.

The CDC's decision followed the U.S. Food and Drug Administration's (FDA) emergency use authorization (EUA) of both vaccine boosters for all adults earlier on Friday.

The FDA's vaccine advisory panel--the Vaccines and Related Biological Products Advisory Committee--had originally rejected both vaccine's EUA submissions to authorize booster doses for all adults back in September, recommending the shots only for more vulnerable Americans due to lack of compelling evidence. Pfizer-BioNTech and Moderna then resubmitted new data last week, which gave greater evidence that vaccine efficacy wanes over time, prompting the FDA's advisory panel to then recommend booster doses to all Americans over the age of 18.

"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 olders," said Dr. Peter Marks, head of the FDA's Center for Biologics Evaluation and Research, in a press statement. "Streamlining the eligibility criteria and making booster doses available to all individuals 18 years of ages and older will help eliminate confusion about who may receive a booster dose and ensure booster doses are available to all who may need one."

The U.S. has fully vaccinated more than 196 million Americans, or about 59% of its total population, according to data compiled by the CDC. By vaccine, nearly 109 million people have been fully vaccinated by the Pfizer-BioNTech vaccine, about 72 million by Moderna, and roughly 16 million by Johnson & Johnson (JNJ  ). The U.S. has currently administered 35.4 million booster doses.

The CDC continues to encourage the 47 million adults who are not yet vaccinated to get vaccinated as soon as possible to protect themselves and their families and loved ones. The agency also strongly encourages older population and individuals with underlying medical condition to receive a booster dose before the holidays.