Though China’s factories still produce a mind-bending array of relatively simple, low-value products like clothing and plastic goods, they have long since achieved dominance in more advanced and lucrative pursuits like smartphones, computers and auto parts. The country has evolved into an essential part of the global supply chain, producing components needed by factories from Mexico to Malaysia.

China has also risen into an enormous consumer market, a nation of 1.4 billion people with a growing appetite for electronic gadgets, fashion apparel and trips to Disneyland.

The trade war waged by the Trump administration has prompted a partial decoupling of the United States and China, the two largest economies on earth. Multinational companies that have used factories in China to make their wares have sought to avoid American tariffs by shifting production to other countries — especially Vietnam. The coronavirus might accelerate that trend, at least for a time, should global companies find themselves locked out of China.

The outbreak of the virus in Wuhan, a city that is home to 11 million people, prompted the Chinese government to effectively quarantine the metropolis and much of surrounding Hubei province, barring people from moving around.

Until now, the impact on factories was limited by the fact that the outbreak was unfolding during the Lunar New Year, the most important holiday of the year. Many businesses are closed during the holiday, while hundreds of millions of migrant workers return home to their families in the countryside.

In a bid to keep people home and halt the spread of the virus, the government extended the holiday through Sunday, adding three days. But the fear of the virus is so widespread and intense that many workers are likely to remain away from factory towns this week.