BEIJING (AP) — Everyone in a district of 1.8 million people in China’s southern metropolis of Guangzhou was ordered to stay home for virus testing Saturday and a major city in the southwest closed schools as another rise in COVID-19 infections was reported.

Nationwide, a total of 11,773 infections were reported over the previous 24 hours, including 10,351 people with no symptoms. China’s numbers are low, but the past week’s increase is challenging a “zero-COVID” strategy that aims to isolate every infected person.

The quarantine for travelers arriving in China is to be shortened to a minimum of five days from seven as part of changes in controls announced Friday to reduce their cost and disruption. But the ruling Communist Party said it would stick to “zero COVID” even as other countries ease travel and other curbs and try to shift to a long-term strategy of living with the virus.

A total of 3,775 infections were found in Guangzhou, a city of 13 million, including 2,996 in people who showed no symptoms, according to the National Health Commission. That was an increase from Friday’s total of 3,030, including 2,461 without symptoms.

People in the Guangzhou’s Haizhu district were told to visit the nearest testing station but otherwise stay home, the district government announced on its social media account. One member of each household was allowed out to buy food.

Also Saturday, health officials warned the decision to modify anti-virus controls didn’t mean they were ending.

Under the changes, some foreign businesspeople and athletes visiting China would be allowed to move within a contained area without a quarantine period. Rules on who counts as a contact of infected people are to be more focused, reducing the number affected.

“This is not relaxation, nor ‘lying flat,’ but more accurate and scientific prevention and treatment,” said the NHC deputy director, Lei Haichao. Lei said the goal is to “prevent the epidemic and minimize the impact on economic and social development.”

Economists and public health experts say Beijing might be able to start winding down “zero COVID” in mid-2023 but needs to vaccinate tens of millions of elderly people before controls on foreign visitors coming into China end.

Nationwide, people who want to enter supermarkets and other public buildings are required to show negative results of a virus test taken as often as once a day. That allows authorities to spot infections in people with no symptoms.