The Centers for Disease Control and Prevention (CDC) on Monday updated agency guidance to advise that anyone over age 18 should receive a COVID-19 booster shot.

"Today, CDC is strengthening its recommendation on booster doses for individuals who are 18 years and older. Everyone ages 18 and older should get a booster shot either when they are 6 months after their initial Pfizer or Moderna series or 2 months after their initial J&J vaccine," CDC Director Dr. Rochelle Walensky said in a press release.

Centers for Disease Control and Prevention Director Rochelle Walensky (L) and NIH National Institute of Allergy and Infectious Diseases Director Anthony Fauci arrive ahead of testifying before the Senate Health, Education, Labor, and Pensions Committee about the ongoing response to the COVID-19 pandemic in the Dirksen Senate Office Building on Capitol Hill on November 04, 2021 in Washington, DC.

Centers for Disease Control and Prevention Director Rochelle Walensky (L) and NIH National Institute of Allergy and Infectious Diseases Director Anthony Fauci arrive ahead of testifying before the Senate Health, Education, Labor, and Pensions Committee about the ongoing response to the COVID-19 pandemic in the Dirksen Senate Office Building on Capitol Hill on November 04, 2021 in Washington, DC. (Chip Somodevilla/Getty Images)

Walensky went on to claim that the new omicron variant of COVID-19 "emphasizes the importance of vaccination, boosters, and prevention efforts needed to protect against COVID-19."

Early data from South Africa suggests the omicron variant is highly transmissible, Walensky explained, for which reason scientists worldwide are "urgently examining vaccine effectiveness related to this variant."

Walensky strongly urged the 47 million adults in the U.S. who have held out on getting vaccinated to do so as soon as possible, and claimed vaccinated children and teens will also help build strong immunity against serious illness.

BIDEN: STRATEGY FOR OMICRON VARIANT IS VACCINATION, NOT SHUTDOWNS

"I also want to encourage people to get a COVID-19 test if they are sick. Increased testing will help us identify Omicron quickly," Walensky concluded, urging Americans to follow the agency's prevention strategies.

Walensky's advice echoed that of President Biden, who on Monday held a press conference at the White House with Dr. Anthony Fauci about the omicron variant, which the World Health Organization designated a "variant of concern," its most serious designation for a COVID-19 variant.

President Biden and Dr. Anthony Fauci

Dr. Anthony Fauci speaks alongside President Joe Biden as he delivers remarks on the Omicron COVID-19 variant following a meeting of the COVID-19 response team at the White House on November 29, 2021 in Washington, DC. (Photo by Anna Moneymaker/Getty Images)

The president stressed that all individuals, whether vaccinated or not, should be wearing masks and face coverings in public settings again.

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During a meeting later in the day with CEOs of various companies about the supply chain crisis, Biden said that Americans who are eligible for a booster shot have "no excuse" for not getting one.

President Biden

President Joe Biden delivers remarks at the start of a hybrid virtual roundtable with CEOs and leaders of retail, consumer products firms, and grocery store chains in the Eisenhower Executive Office Building on November 29, 2021 in Washington, DC. (Photo by Anna Moneymaker/Getty Images)

"In the meantime, I've said the best protection against this new variant is to get fully vaccinated and get a booster shot," Biden said. "And I urge all Americans who haven't yet done that, get it done today. There's no excuse. There are over 80,000 places you can get it done. I mean, there's just there's no reason. It's free, it's available, and if you qualify for the booster, get it done today."