Lifestyle Health CDC 'Strongly Encourages' COVID Vaccine Boosters for All Americans Due to Omicron Variant Two cases of the Omicron variant were discovered in Canada over the weekend in travelers who had recently returned from Nigeria, according to health officials By Katie Campione Katie Campione Digital News Writer, PEOPLE People Editorial Guidelines Published on November 29, 2021 10:24 PM Share Tweet Pin Email Vaccine. Photo: Getty The Centers for Disease Control is expanding its COVID-19 vaccine booster recommendations for Americans following the arrival of the Omicron variant in North America. "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," the CDC said in a statement on Monday. Two cases of the Omicron variant were discovered in Canada over the weekend in travelers who had recently returned from Nigeria, according to health officials. Canada is one of 16 countries that has identified cases of the Omicron variant so far, and the World Health Organization said Sunday that they expect it to spread globally. The spread of the variant "further emphasizes the importance of vaccination, boosters, and prevention efforts needed to protect against COVID-19," the CDC 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." The organization also "strongly" encouraged all adults who are not yet vaccinated to get the shots "as soon as possible." Adults should also seek to have any eligible children or teens in their homes vaccinated, the CDC added. Dr. Fauci 'Would Not Be Surprised' if Omicron COVID Variant Is Already in the United States A person getting vaccinated. Getty The United States has not yet confirmed a case of the Omicron variant, but Dr. Anthony Fauci, the nation's top infectious disease expert, said Saturday that he "would not be surprised" if it already is in the country. "We have not detected it yet [in the U.S.]," he said, "but when you have a virus that is showing this degree of transmissibility and you're already having travel-related cases that they've noted in Israel and Belgium and in other places — when you have a virus like this, it almost invariably is ultimately going to go essentially all over." Omicron Variant Now in North America as Canada Identifies First Cases of the COVID Strain President Joe Biden emphasized Monday, though, that the variant is a "cause for concern, not a cause for panic." "We have the best vaccine in the world, the best medicines, the best scientists, and we're learning more every single day," he said Monday. "We'll fight this variant with scientific and knowledgeable actions and speed, not chaos and confusion." As information about the coronavirus pandemic rapidly changes, PEOPLE is committed to providing the most recent data in our coverage. Some of the information in this story may have changed after publication. For the latest on COVID-19, readers are encouraged to use online resources from the CDC, WHO and local public health departments. PEOPLE has partnered with GoFundMe to raise money for the COVID-19 Relief Fund, a GoFundMe.org fundraiser to support everything from frontline responders to families in need, as well as organizations helping communities. For more information or to donate, click here.