The U.S. will restrict travel from South Africa and seven other countries, effective Monday — a response to the emerging and newly-named "Omicron" variant of COVID-19, according to a senior administration official.
The policy, senior administration officials said Friday, "was implemented out of an abundance of caution," and after advice from the Centers for Disease Control and Prevention and Dr. Anthony Fauci, the chief medical adviser to President Joe Biden.
Other countries included in the restriction include Botswana, Zimbabwe, Namibia, Lesotho, Eswatini, Mozambique and Malawi.
U.S. stocks fell Friday, with the Dow Jones Industrial Average closing its worst day of the year as news of the variant — first detected in South Africa, with cases also identified in Asia and Europe — prompted concerns about prolonged pandemic troubles. The World Health Organization convened for an emergency meeting, and the United Kingdom, the European Union and other countries announced they were restricting travel from the African continent.
The new strain, classified by the WHO as a "variant of concern," is blamed for a surge of cases in South Africa and has sparked fears over its high number of mutations, which make it potentially more transmissible and resistant to vaccines.
“We don't know very much about this yet,” Maria Van Kerkhove, an infectious disease epidemiologist and the WHO’s Covid-19 technical lead said in a Thursday video. “What we do know is that this variant has a large number of mutations. The concern is that when you have so many mutations it can have an impact on how the virus behaves.”
This story first appeared on NBCNews.com.