President Joe Biden will extend until mid-March a requirement that travelers wear masks on airplanes, trains and buses and at airports and transit stations, a person familiar with the decision said Wednesday night.

The move to extend the mandate, which was set to expire Jan. 18, is part of a much broader winter strategy for combating COVID-19 that Biden is to announce Thursday, during a visit to the National Institutes of Health. The strategy will also include a new requirement that international travelers be tested for COVID-19 one day before departing for the United States, according to officials at the Centers for Disease Control and Prevention. The mask mandate extension was first reported by Reuters on Wednesday.

Biden will unveil his strategy as the new variant, known as omicron, is encircling the globe. On Wednesday, health officials in California announced the first confirmed case of the variant in the United States, in a patient in San Francisco who arrived Nov. 22 from South Africa.

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The president has already imposed travel restrictions on people coming to the United States from eight African nations, including South Africa. Biden said earlier this week that the restrictions were intended to buy the administration time; his science advisers, including Dr. Anthony Fauci, the nation’s leading infectious disease specialist, have made clear that it would only be a matter of time before the variant arrived in the United States.

Much is unknown about the omicron variant. First identified in Botswana and South Africa, it has prompted concern among scientists and public health officials because of an unusually high number of mutations that have the potential to make the virus more transmissible and less susceptible to existing vaccines.