On Monday, the Centers for Disease Control and Prevention (CDC) strengthened its recommendation on COVID boosters amid growing concerns over the Omicron variant, according to CNBC.

The CDC is urging adults to get an additional dose due to growing concern about Omicron, another highly contagious COVID strain first identified in Botswana, a country in southern Africa.

CDC Director Dr. Rochelle Walensky said in a statement, “The recent emergence of the Omicron variant (B.1.1.529) further emphasizes the importance of vaccination, boosters, and prevention efforts needed to protect against COVID-19.”

Earlier this month, the CDC approved booster doses for all people aged 18 and over. And now the agency has given its strongest recommendation for everyone ages 18 and older, saying they should get an additional dose six months after their initial Pfizer-BioNTech or Moderna jabs, or two months after a single-dose Johnson & Johnson shot.

On Sunday, the World Health Organization (WHO) warned that the global risk posed by the Omicron variant is “very high.” The strain has about 32 mutations on its spike protein alone. The WHO said these mutations could fuel surges of infection with “severe consequences.”

Dr. Walensky said, “Early data from South Africa suggest increased transmissibility of the Omicron variant, and scientists in the United States and around the world are urgently examining vaccine effectiveness related to this variant.”

Omicron is believed to be highly contagious than the Delta variant, but it is unclear how much the latest strain will affect the strength and efficacy of currently available vaccines.

Pfizer and Moderna said they would have more data in about a couple of weeks.

Albert Bourla, Pfizer CEO, told CNBC, “I don’t think that the result will be the vaccines don’t protect. I think the result could be, which we don’t know yet, the vaccines protect less.” He said the company can develop a new vaccine within 100 days.

Stephane Bancel, Moderna CEO, told CNBC that the company could deploy a higher-dosage booster dose against the new strain quickly but a variant-specific vaccine could take months.

So far, there have been no cases of Omicron in the U.S., but President Joe Biden said the nation will face the variant sooner or later, urging all Americans to get booster shots for added protection.

Dr. Walensky urged people to get tested as well. She said, “I also want to encourage people to get a COVID-19 test if they are sick. Increased testing will help us identify Omicron quickly.”