University of Michigan suspends athletic activities after finding multiple cases of the British-affiliated variant.

The University of Michigan said Saturday that it had suspended all sports activities for up to two weeks and told athletes, coaches and team staff members to quarantine immediately after “several” cases of the British-affiliated variant of the coronavirus were found among people linked to the athletic department.

The department said the suspension had been mandated by the Michigan Department of Health and Human Services in an effort to prevent further spread of the variant, known as B.1.1.7, which is estimated to be about 50 percent more transmissible than other variants.

“Canceling competitions is never something we want to do,” Warde Manuel, the University of Michigan athletic director, said in a statement, “but with so many unknowns about this variant of Covid-19, we must do everything we can to minimize the spread among student-athletes, coaches, staff, and to the student-athletes at other schools.”

Michigan, a member of the Big Ten Conference, has one of the most prominent athletic programs in the country. Its men’s basketball team is currently ranked seventh nationally, and the women’s team is ranked 11th. A two-week suspension would require both teams to reschedule or cancel at least four games.

Officials in Washtenaw County, which includes the University of Michigan, said Saturday that five cases of the B.1.1.7 variant had been found in the county and that other possible cases were being investigated. They said that the first case was detected on Jan. 16 within the University of Michigan community, but that it was not clear whether the subsequent cases were related to the first one.

The university administration said five cases of the variant had been detected among people associated with the school. It added that all five people were in isolation and experiencing mild or no symptoms, and that all of their close contacts had been identified, tested and placed in quarantine.

The coronavirus has disrupted college sports programs across the country, with thousands of infections among athletes, coaches and staff members. A New York Times analysis last month found that the Big Ten Conference had reported the most cases of any top league, including more than 200 at Michigan.

The first U.S. case of the B.1.1.7 variant was found in Colorado last month, and it has now been detected in 22 states. Federal health officials have warned that it may become the country’s dominant source of coronavirus infection by March.