In the central Chinese city of Xi’an, 13 million people are dealing with one of the world’s strictest coronavirus lockdowns.

Residents have been ordered to stay in their homes since Monday, with city officials rushing truckloads of vegetables from one apartment complex to the next to try to keep people supplied with food.

The severe containment measures — reminiscent of the initial lockdown in Wuhan in early 2020 — underline China’s determination to stick to a “zero covid” policy designed to stamp out infections, even as the country’s vaccination rate exceeds 85 percent.

The approach comes at a cost, however, especially given the specter of more-transmissible variants. All nonessential production has been suspended in Xi’an, according to state media, and U.S. chipmaker Micron and Korean electronics giant Samsung have warned of disruptions as their facilities in the area have been affected.

The number of coronavirus infections in Xi’an — an ancient Silk Road city known for the terra cotta warriors — may seem minuscule compared with other countries: Xi’an reported 155 new cases on Wednesday, bringing its total to over 1,100. New York City, which has fewer residents than Xi’an, tallied a record 39,591 new cases the same day.

But everything is relative. Xi’an was the source of all but one case of domestic coronavirus transmission across China on Wednesday, according to the National Health Commission, and the city’s case count has returned to its highest levels in two years.

That puts enormous pressure on the city’s officials to bring the outbreak to heel. China will host the Winter Olympics in February, and top leaders have been anxious to put their best foot forward for the event.

Chinese authorities have not said whether any of the cases in Xi’an were caused by the omicron variant.

At a news conference on Wednesday, a health commission official criticized Xi’an for cases of transmission to other provinces and said the city needed to strengthen its pandemic controls.

When the lockdown began last week in Xi’an, each family was allowed to send one person out every two days to procure food and supplies, but this was tightened on Monday to prohibit any trips out, except for coronavirus testing.