The United States will require a Covid-19 test for travelers from China, due to the explosion in the number of cases in that country and the lack of information communicated by Beijing, US health authorities announced yesterday.

The measure comes into force on January 5, and "all air passengers aged 02 and over from China will be required to take a test no later than two days before departure", regardless of their nationality or vaccination status, the Centers for Disease Control and Prevention (CDC) said in a statement.

The CDC specified that this measure will also apply to passengers coming from Hong Kong and Macau.

The United States is particularly concerned that the rapid transmission of the virus in China will cause new variants to emerge.

A US official criticized "the lack of adequate and transparent sequencing data" provided by China.

In addition, "testing and counting of new cases has decreased" in China, making it more difficult for US health authorities to identify new variants circulating in the country with "the lack of available data", added the same source, quoted by Agence France-Presse (AFP) and Lusa.

The tests will have to be presented to the airlines at the time of departure, said the CDC, with PCR or antigen tests being accepted, as well as proof of recovery from covid-19 after a positive test, more than 10 days before the flight.

This decision follows similar announcements by several countries, including Japan and India, which have also imposed mandatory tests on Chinese arrivals.

The Chinese authorities ended most of the measures against covid-19 without warning on December 7, amid growing public exasperation and a huge impact on the economy after three years of restrictions.

Since then, China has seen an explosion in the number of cases among its 1.4 billion inhabitants, with hospitals and crematoria being overwhelmed and residents reporting a shortage of fever medication.

Last week, the World Health Organization (WHO) expressed "serious concern" about the wave of new Covid-19 cases in China, and called on Beijing to be more transparent in order to deal with future pandemics.

Covid-19 is an infectious respiratory disease caused by SARS-CoV-2, which was detected in late 2019 in China and has spread rapidly around the world.