The US has implemented new measures requiring travelers from China to take a Covid test over growing concerns about an increase in cases.

While the US has largely ended its own strict Covid policies, this latest move comes amid growing concerns about the state of China. China recently ended its strict Covid policies and has experienced a significant increase in cases as a result.

According to Politico, US officials are also worried about the possibility of new variants coming out of China.

“Predeparture testing and the requirement to show a negative test result decreases the number of infected passengers boarding airplanes and it will help to slow the spread of the virus as we work through identifying and understand any potential new variants that may emerge,” a federal health official told reporters.

Travelers from South Korea’s Incheon International Airport, Toronto Pearson International Airport and Vancouver International Airport will also be required to have a negative Covid test two days before coming to the US if they have been to China in the previous 10 days.

Officials hope this latest measure, in combination with other CDC recommendations, will help slow the spread and reduce the likelihood of new strains.

“We know these measures will not eliminate all risk or completely prevent people who are infected from entering the United States,” the federal health official said. “But taken together they will help limit the number of infected people and provide us an early warning about new variants.”