The United States will require negative COVID-19 tests from all travelers from China, joining other nations imposing restrictions because of a surge of infections.

The new rules take effect on January 5, two days before China ease its own restrictions on travel to and from the country.

"All air passengers two years and older originating from China will be required to get a test no more than two days before their departure from China, Hong Kong and Macau, and show a negative test result to the airlines upon departure," a US federal health official said.

Other countries, including Japan, India, and South Korea, have taken similar steps to keep infections from spreading beyond China's borders.

China is in the midst of an unprecedented surge in COVID-19 cases but observers say official statistics hide the true extent of the wave.

"The recent rapid increase in Covid-19 transmission in China increases the potential for new variants emerging," US official told reporters in a phone briefing. "Based on this lack of available data, it's harder for US public health officials to identify new variants spreading to the United States," the official added.

Italy also introduces mandatory testing on visitors from China

Earlier on Wednesday, Italy's health minister said that it was making coronavirus tests for visitors from China mandatory.

"I have ordered mandatory COVID-19 antigenic swabs, and related virus sequencing, for all passengers coming from China and transiting through Italy," Italian Health Minister Orazio Schillaci said.

"The measure is indispensable to guarantee surveillance and identification of any new variants of the virus in order to protect the Italian population," Schillaci was cited by Italian daily newspaper Il Corriere della Sera as saying.

The northern region of Lombardy already introduced the measure on Tuesday. Italy's foreign ministry said that the region will test arrivals at Milan's Malpensa airport at least until January 30.

Lombard health chief Guido Bertolaso said that on the first two flights from China that were screened for coronavirus, 46% of passengers tested positive, according to Il Corriere della Sera.

Swabs collected at the Malpensa are being analyzed by the national health ministry.

China opening up

China's abandonment of COVID-zero policies has revived the prospect of outbound tourism for the first since early 2020.

From January 8, people landing in China — including returning Chinese nationals — will no longer have to quarantine for five days.

The passport application process will also resume from that date.

The announcement caused a surge in traffic to Chinese travel websites as airlines race to bring international routes back online.

Japan tightens rules for visitors from China

Elsewhere, Japan announced Tuesday that it will tighten its border by requiring tests for all visitors from China, starting Friday.

For now it is seen as a temporary emergency measure against the surging number of COVID infections there.

Last week, India also mandated COVID tests for travelers arriving from China, Japan and several other Asian countries.

In response to questions about Indian and Japanese requirements for Chinese travelers, China's foreign ministry said on Tuesday that "COVID measures should be scientific, moderate and should not affect the normal flow of individuals."

Malaysia has also announced increased tracking and surveillance measures in response to the situation in China.