U.S. considers airline wastewater testing as Covid surges in China
An Air China Boeing 747-8 makes its final landing at New York’s John F. Kennedy International Airport on January 23, 2020.
Nicolas Economou Nurfoto | Getty Images
As Covid-19 infections rise in China, the US Centers for Disease Control and Prevention is considering sampling sewage taken from international planes to track any emerging new variants, the agency told Reuters.
Such a policy would offer a better solution to tracking the virus and slowing its entry into the United States than the new travel restrictions announced this week by the US and other countries, which require mandatory negative tests Covid for travelers from China, three infectious disease experts said. Reuters.
Travel restrictions, such as mandatory testing, have so far failed to significantly curb the spread of Covid and function mainly as optics, said Dr. Michael Osterholm, an infectious disease expert at the University of Minnesota.
“They seem to be essential from a political point of view. I think every government feels like they will be accused of not doing enough to protect their citizens if they don’t do these,” he said.
The United States this week also expanded its voluntary genomic sequencing program to airports, adding Seattle and Los Angeles to the program. This brings the total number of airports collecting information from positive tests to seven.
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But experts said that may not provide a meaningful sample size.
A better solution would be to test sewage from airlines, which would provide a clearer picture of how the virus is changing, given the lack of data transparency in China, said Dr Eric Topol, a genomics expert and director of the Scripps Research Translation Institute in La Jolla. California.
Removing sewage from aircraft from China “would be a very good tactic,” Topol said, adding that it is important for the United States to improve its surveillance tactics “because China is not so willing to share its genomic data”.
China has said criticism of its Covid statistics is unfounded and played down the risk of new variants, saying it expects the mutations to be more infectious but less severe. However, doubts over official Chinese data have led many countries, including the United States, Italy and Japan, to impose new testing rules on Chinese visitors after Beijing lifted travel controls.
Analysis of aircraft sewage is among several options the CDC is considering to help slow the introduction of new variants into the United States from other countries, CDC spokeswoman Kristen Nordlund said in an email.
The agency is grappling with a lack of transparency about Covid in China after the country of 1.4 billion suddenly lifted strict lockdown measures and testing policies for Covid, unleashing the virus on an under-vaccinated and previously unexposed population.
“Previous Covid-19 wastewater surveillance has shown to be a valuable tool, and in-flight wastewater surveillance could potentially be an option,” she wrote.
French researchers reported in July that tests of aircraft sewage showed that requiring negative Covid tests before international flights did not protect countries from the spread of new variants. They found the omicron variant in sewage from two commercial planes that flew from Ethiopia to France in December 2021, even though passengers had been required to take Covid tests before boarding.
California researchers reported in July that sampling of community sewage in San Diego revealed the presence of alpha, delta, epsilon and omicron variants up to 14 days before they started showing up on nasal swabs.
Osterholm and others said mandatory pre-travel testing in the United States is unlikely to keep new variants out of the country.
“Closing borders or testing borders really makes very little difference. It probably slows it down by a few days,” he said, because the virus is likely to spread around the world and infect people in Europe or elsewhere, who then can bring it to the United States.
David Dowdy, an infectious disease epidemiologist at the Johns Hopkins Bloomberg School of Public Health, said increased genomic surveillance is important and sampling sewage can be helpful, but testing takes time.
“I think we have to be careful in how much we expect this data to be able to really inform our ability to respond,” he said.