(Dec 29): The US will require airline passengers coming from China to show negative Covid-19 tests as global concerns over the virus’s spread ratchet higher since the country lifted restrictions aimed at stamping out infections.

Travellers coming directly from China or who were in the country 10 days before their departure to the US will have to show either a negative PCR or antigen test for the coronavirus, federal health officials said Wednesday, speaking on condition of anonymity in a call with reporters. The requirement applies to all passengers regardless of nationality or vaccination status and will go into effect Jan 5 at 12.01am New York time.

Passengers who tested positive more than 10 days before travelling can provide documentation and recovery from Covid in lieu of a negative test result, the officials said on the call. Airlines will need to confirm the negative Covid test or documentation of recovery prior to boarding flights to the US. The requirement also applies to travellers from Hong Kong and Macau.

Covid has been spreading unabated in China since the government lifted its policy of strict quarantines and isolation for exposed and infected people. Almost 37 million people may have been infected with the virus on a single day last week, according to estimates from the Chinese government’s top health authority.

The US Centers for Disease Control and Prevention will also expand its viral genomic surveillance programme of travellers to two additional airports, bringing the total number collecting samples for sequencing to seven. Passengers boarding hundreds of flights from at least 30 countries are covered by the programme.

US health officials had been considering taking new coronavirus precautions for travellers from China amid concerns over lack of transparency around case data, Bloomberg reported earlier. US health experts are particularly concerned about the emergence of new variants that might not be picked up in testing in China, the officials said on the call. Health officials said they’ll continue to press China to release data and genome sequences of the virus.

The high number of people affected over a very short period of time raises the chances of a new variant emerging, health officials said. China is submitting few sequences of the virus to an international database that tracks mutations, the officials said. New mutations can make the virus more transmissible or more deadly.

For the past three years, Chinese officials have adhered to stringent rules around testing and quarantines that were often subject to international criticism. Earlier this month, after widespread protests against the restrictive policies, Chinese officials abruptly announced lifting of the restrictive policies without a plan for simultaneously boosting vaccination coverage.

That’s allowed the virus to spread rapidly, filling health-care facilities with sick patients, most without immunity from vaccination or prior infections like the majority of people in other countries.

Italian health authorities said earlier Wednesday that they will begin testing all arrivals from China for Covid after nearly half of passengers on two flights to Milan were found to have the virus. Countries such as Japan, Malaysia and India are also ramping up tracking and surveillance measures.  

Covid testing at US airports has tapered off as countries have abandoned pandemic-era travel restrictions. However, US health officials said that voluntary testing and sequencing at airports has continued and will be further expanded under a new effort to ramp up precautions amid the outbreak in China.

When the Covid Delta variant first emerged in late 2021, the CDC partnered with Ginkgo Bioworks Holdings and other companies to collect and sequence samples from travellers who arrived in the US from India. When Omicron cropped up, that programme was expanded.

Today the majority of infections worldwide are from a slew of different Omicron subvariants that mutated to become more transmissible and immune-evasive. Mutations can also make the virus deadlier, highlighting the importance of closely tracking them, and many antibody treatments have already been rendered ineffective by new variants.