The United States is considering sampling wastewater taken from international aircraft to track any emerging new Covid-19 variants as infections surge in China, as UK-based health experts estimate about 9,000 people a days are now dying of the disease in China.
The proposed of testing wastewater by the US Centers for Disease Control and Prevention would provide a better solution to tracking the virus and slowing its entry into the US than new travel restrictions announced this week, three infectious disease experts said.
The US and a number of other countries have said travellers from China will require mandatory negative Covid tests.
Their comments came as UK-based health data firm Airfinity said about 9,000 people in China were probably dying each day from Covid, nearly doubling its estimate from a week ago.
Covid infections started to sweep across China in November, picking up pace this month after Beijing dismantled its zero-Covid policies including regular PCR testing on its population and publication of data on asymptomatic cases.
Cumulative deaths in China since 1 December likely reached 100,000, with infections totalling 18.6m, Airfinity said in a statement on Thursday. It used modelling based on data from Chinese provinces before the recent changes to reporting cases were implemented, it said.
Airfinity expects China’s Covid infections to reach their first peak on 13 January with 3.7m cases a day.
Their figures were in contrast to the several thousands of cases reported by Chinese health authorities a day, after a nationwide network of PCR test sites was largely dismantled and authorities pivoted from preventing infections to treating them.
The European Union’s health agency said on Thursday it believed the EU-wide introduction of mandatory Covid screenings for travellers from China was currently “unjustified”, pointing to the “higher population immunity in the EU/EEA, as well as the prior emergence and subsequent replacement of variants currently circulating in China”.
But in a series of tweets, the World Health Organization chief, Tedros Adhanom Ghebreyesus, renewed his appeal to China to be more forthcoming with detailed data on the pandemic situation in the country.
“In the absence of comprehensive information from China, it is understandable that countries around the world are acting in ways that they believe may protect their populations,” Tedros wrote.
Airfinity expects deaths to peak on 23 January with about 25,000 a day, with cumulative deaths reaching 584,000 since December. Since 7 December, when China made its abrupt policy U-turn, authorities have officially reported just 10 Covid deaths.
Internationally, travel restrictions such as mandatory testing have so far failed to significantly curb the spread of Covid and function largely as optics, said Dr Michael Osterholm, an infectious disease expert at the University of Minnesota.
“They seem to be essential from a political standpoint. I think each government feels like they will be accused of not doing enough to protect their citizens if they don’t do these,” he said.
The US this week also expanded its voluntary genomic sequencing program at airports, adding Seattle and Los Angeles to the program. That brings the total number of airports gathering information from positive tests to seven.
But experts said that might not provide a meaningful sample size.
A better solution would be testing wastewater from airlines, which would offer a clearer picture of how the virus was mutating, given China’s lack of data transparency, said Dr Eric Topol, a genomics expert and director of the Scripps Research Translational Institute in La Jolla, California.
Getting wastewater off planes from China “would be a very good tactic”, Topol said, adding that it was important the US upgrade its surveillance tactics “because of China being so unwilling to share its genomic data”.
China has said criticism of its Covid statistics is groundless, and played down the risk of new variants, saying it expects mutations to be more infectious but less severe. Still, doubts over official Chinese data have prompted many places – including Italy and Japan as well as the US – to impose new testing rules on Chinese visitors as Beijing lifted travel controls.
Airplane wastewater analysis is among several options the Centers for Disease Control and Prevention is considering to help slow the introduction of new variants into the US from other countries, a spokesperson for the agency, Kristen Nordlund, said.
“Previous Covid-19 wastewater surveillance has shown to be a valuable tool and airplane wastewater surveillance could potentially be an option,” she said in an email.
French researchers reported in July that airplane wastewater tests showed requiring negative Covid tests before international flights does not protect countries from the spread of new variants. They found the Omicron variant in wastewater from two commercial airplanes that flew from Ethiopia to France in December 2021 even though passengers had been required to take Covid tests before boarding.
Reuters and Agence France-Presse contributed to this report
