Shipyards around the country have run into labor shortages, said Tim Huxley, the chief executive of Mandarin Shipping, a Hong Kong freighter shipping company. Shipbuilders and ship repair providers have begun citing these labor shortages to invoke clauses in their contracts that allow them to delay completion of projects for events beyond their control, he said.

Aside from fear of disease, the country’s nearly 300 million migrant workers — almost two-fifths of the labor force — now have another reason to be reluctant to travel to distant cities: Their children are still home. Depending on the province, many schools are not scheduled to resume until Feb. 25 or even March 1.

Even factories with enough workers are running into further problems. The packaging industry is almost shut down, so everything from plastic packing to steel drums is running out, Mr. Wuttke said.

Local regulators are putting up even more barriers.

Before businesses in big manufacturing hubs like Shanghai, Shenzhen, Suzhou or Nanjing can reopen, they must now verify the travel history and health of every employee over the past two weeks. They must have frequent temperature checks of employees, hand-washing procedures and a plan to isolate and refer to hospitals anyone showing even fevers as low as 99.1 degrees Fahrenheit.

Most difficult of all, businesses cannot reopen without approval of their health plans by municipal officials — and larger operations also have to wait for a site visit from a health official.

Shenzhen, a vast sprawl of electronics factories and skyscrapers next to Hong Kong, issued new health and safety rules on Sunday and said factories that made iPhones and other Apple products would have to meet them before opening. Foxconn Technology, a Taiwanese company that owns the factories, said it met all health and hygiene rules but declined to comment on when production would restart at specific locations. Apple declined to comment.