The eastern Swiss canton of Grisons ordered everyone to wear masks in the town of 5,200 residents that prides itself as a birthplace of modern winter sports. Mass testing of residents will take place on Tuesday. Schools and daycare venues are closed.
"About a dozen cases are currently known in two hotels. To protect the health of the population and guests, the health department has quarantined the two hotels and ordered corona tests for their employees and guests," the canton said in a statement.
It declined to name the hotels and said it assumed foreigners were among the guests but it did not give their nationalities.
The canton said authorities had identified the N501Y virus mutation, which has been reported in the variants first identified in both Britain and South Africa. The canton did not immediately say if the variant was believed to have come from Britain or South Africa.
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While closing restaurants, bars, theaters and recreational venues to limit spread of the disease, Switzerland has left ski lifts open as long as they maintain measures like mask wearing to protect public health. St. Moritz ski areas remain open, as well, following the variant outbreak.