Industries from auto sales to travel to retailing effectively shut down after curbs were imposed starting Jan. 23 with the suspension of most access to Wuhan, an industrial metropolis of 11 million people at the center of the outbreak.

China’s vast manufacturing industries cannot function without workers in factories. But as some businesses reopen, Beijing has told anyone who still can work from home to stay there.

China’s worst health crisis in years has sparked fear and uncertainty for businesses from North America to Asia that depend on trade in the affected region.