The Biden administration will require airline passengers traveling from China to test negative for Covid before entering the U.S. as concern grows that widespread transmission of the virus in the world’s most populous country could result in new variants.

All airline passengers 2 years and older originating from China, Hong Kong or Macau will be required to get tested for Covid-19 no more than two days before their flight to the U.S. and show a negative result to the airline upon departure, the Centers for Disease Control and Prevention announced on Wednesday.

Travelers flying from China to the United States will be required to show proof of a negative COVID-19 test before they board starting on Jan. 5, the Centers for Disease Control and Prevention announced Wednesday.

Passengers two years and older will be required to show a negative PCR or antigen test taken within two days before departure at the gate, the CDC said in a press release.

The United States will require travelers from China, Hong Kong and Macau to show a negative COVID-19 test before entering the U.S. as restrictions lessen and cases surge in China.

The U.S. Centers for Disease Control and Prevention announced the measure Wednesday to go into effect on Jan. 5 for all passengers over the age of 2. Passengers must show a negative PCR or monitored antigen test no more than two days before their departure, whether it is a direct flight or an indirect one through another country.