Residents in Beijing should avoid going to Tianjin, as 40 confirmed COVID-19 cases were found there over the weekend, capital officials said on Sunday.

The Beijing Center for Disease Prevention and Control reminded the public that because cases of the Omicron variant were reported in Tianjin, and many people commute from there to work in Beijing, everyone should be aware of the risks. Cross-city commuters are asked to work at home instead of coming to the capital.

It takes about half an hour to travel by high-speed rail from Tianjin to Beijing.

Starting on Sunday afternoon, the railway authority suspended tickets sales from Tianjin to Beijing. Check points have been set up on expressways, and all passengers should show proof of negative test results to pass.

Tianjin launched mass COVID-19 testing on Sunday. The first two cases, a 10-year-old student and a 29-year-old employee of an after-school tutoring center, were identified on Saturday morning.

Genome sequencing showed that they had contracted the highly transmissible Omicron variant, according to Tianjin’s task force leading the disease control effort.

People are advised to not leave Tianjin unless it is absolutely necessary. Travelers who must leave the city are required to show their health codes and negative nucleic acid test results no older than 48 hours.

To reduce cross-city travel, many cities in China are encouraging residents to stay put for the Chinese Lunar New Year, which falls on Feb 1 this year, instead of going back to their hometowns.