Health experts and international organizations have criticized the requirement by some countries for travelers from China to have a negative COVID-19 test as a condition for entry, saying it will not help prevent the spread of the virus.

The United States, Canada, India, the United Kingdom, Japan and Australia are among the countries that have announced tougher measures on travelers from China where the BF.7 strain — a shortened name for the BA.5.2.1.7 Omicron variant — is prevalent.

Kerry Bowman, an assistant professor at the University of Toronto's Temerty Faculty of Medicine, said that Canada's requirement for travelers from China to have proof of a negative COVID test was a political move not based on science.

"This isn't the early days of the pandemic," he said, according to The Canadian Press, the national news agency. "So, I do think it's largely political."

Isaac Bogoch, an associate professor at the same faculty, told The Canadian Press that focused and targeted travel measures don't do much to prevent the spread of COVID. Canada was unable to prevent variants of the Alpha, Delta and the Omicron strains from entering the country, Bogoch said.

"Requiring a negative PCR(polymerase chain reaction) test from Chinese travelers, from a science and medical standpoint, will not have much impact for Canada," he added.

Australia's chief medical officer, Professor Paul Kelly, said in a Dec 31 letter to the country's health minister, Mark Butler, that, "I do not believe that there is sufficient public health rationale to impose any restriction or additional requirements on travelers from China."

He said "there is no specific threat from a variant with increased pathogenicity and immune escape", adding Australia has very high levels of vaccination, especially among members of the population most at risk from the virus.

"The BF.7 Omicron subvariant that appears to be a key driver to the outbreak in China has been present in Australia for some time and has been superseded by other circulating subvariants," Kelly said.

Fiona Russell, an infectious diseases epidemiologist from the University of Melbourne, said predeparture testing of travelers from one country alone would have a "very minimal impact" on preventing importation of new variants.

Russell said in an interview with the Australian Broadcasting Corporation that people in China could be deterred from taking a supervised test to travel overseas because of fears of "discriminatory policies".

French epidemiologist Dominique Costagliola said that given that France is currently reducing its capacity to sequence the virus, testing arrivals from China seems little more than a "communication" exercise. "It is not very useful, apart from giving the impression that we are doing something," she told Agence France-Presse.

International Air Transport Association Director General Willie Walsh criticized countries for introducing COVID-19 testing and other measures for travelers from China, "even though the virus is already circulating widely within their borders".

"It is extremely disappointing to see this knee-jerk reinstatement of measures that have proved ineffective over the last three years," Walsh said in a statement.

Airports Council International Europe released a statement expressing "regret regarding the actions of a number of states within the EU and globally for unilaterally imposing health-related travel requirements including systematic pre-departure or on-arrival testing of travelers from China".

China's Foreign Ministry spokeswoman Mao Ning called on Wednesday for science-based and proportionate COVID-19 response measures.

"They should not be used for political manipulation, there should not be discriminatory measures against certain countries, and measures should not affect normal travel and people-to-people exchanges and cooperation," she said.

New Zealand's minister for COVID-19 response, Ayesha Verrall, announced on Wednesday that her country will not require travelers from China to be tested for the virus, saying there was minimal health risk to the public.

"We know that BF.7 is the prevalent variant in China and that it hasn't caused significant outbreaks in other countries that, like New Zealand, have already been exposed to the BA.5 variant. So public health measures are not required to protect New Zealanders," she said in a Radio New Zealand interview.

Verrall said scientists from the country's Institute of Environmental Science and Research would begin a program to test wastewater from international flights to detect the virus in the coming weeks.

Rather than looking at China, many virus experts have turned their attention to the US and the rapidly spreading XBB.1.5 Omicron subvariant.

It has jumped from less than 10 percent of new infections in mid-December to about 40 percent at the end of the month, according to the US Centers for Disease Control and Prevention's COVID-19 tracker.

Paul Hunter, a professor of medicine at the UK's University of East Anglia, told AFP that the main future concern for the UK is the XBB.1.5 variant, which has probably already entered the country from the US and is now spreading.