As new covid crown cases surge in China, the United States considers testing wastewater from international flights

Passengers holding Chinese passports queuing at an international flight counter at Beijing International Airport. (29 December 2022)

WASHINGTON — The U.S. Centers for Disease Control and Prevention told Reuters that as the number of new coronavirus infections in China surges, it is considering sampling wastewater from international flights to track any emerging variants.

Three infectious disease experts told Reuters the policy would provide a better solution for tracking the virus and slowing its entry into the U.S. than the new travel restrictions announced this week by the United States and several other countries. The United States and other countries require mandatory negative coronavirus tests for travelers from China.

Dr. Michael Osterholm, an infectious disease expert at the University of Minnesota. Michael Osterholm said that so far, travel restrictions such as mandatory testing have failed to significantly curb the spread of the coronavirus, and have largely had a visual effect.

“From a political point of view, these measures seem essential. I think every government feels that if they don’t, they’re accused of not doing what they can to protect their citizens. ”

This week, the U.S. also expanded its voluntary genome sequencing program at airports, with Seattle and Los Angeles joining the program. This brings the total number of airports collecting positive test information to seven.

But experts say that may not provide a meaningful sample size.

Dr. Eric Topol, a genomics expert, and director of the Scripps Research Translational Institute in La Jolla, Calif., said a better solution would be to test wastewater from international flights, which would give a clearer picture of how the virus mutated given China’s lack of data transparency.

Topol said taking wastewater from planes coming from China “would be a very good strategy,” adding that it was important for the U.S. to upgrade its surveillance strategy “because China is very reluctant to share its genomic data.” ”

China said criticism of its coronavirus statistics was baseless and downplayed the risk of new virus variants, saying it expected mutations to be more contagious but less deadly. Still, as Beijing lifts travel restrictions, skepticism about official Chinese data has prompted many places, including the United States, Italy, and Japan, to introduce new testing rules for Chinese visitors.

Kristen Nordlund, a spokeswoman for the U.S. Centers for Disease Control and Prevention, said in an email that aircraft wastewater analysis is one of several approaches the CDC is considering to help slow the import of new variants from other countries.

The WHO is grappling with a lack of transparency about the coronavirus in China after a country of 1.4 billion people abruptly lifted strict coronavirus lockdowns and testing policies, releasing the virus into under-vaccinated and previously unexposed populations.

Nordlund wrote in an email: “Previous coronavirus wastewater monitoring has proven to be a valuable tool, and aircraft wastewater monitoring may be an option.”

French researchers said in a report published in July that plane wastewater tests showed that requiring negative nucleic acid test results for passengers on international flights before boarding did not protect the country from the spread of the new variant of the virus. They found the Obi Keron variant in the wastewater of two commercial aircraft flying from Ethiopia to France in December 2021, even though passengers were required to take nucleic acid tests before boarding.

Researchers in California reported in July that the Alpha, Delta, Epsilon, and Omicron variants were found in community wastewater samples in San Diego 14 days earlier than they began appearing on nasal swabs.

Osterholm and others say mandatory testing before traveling to the U.S. are unlikely to stop new variants from entering the country.

“It really makes no difference to close the border or do border testing,” he said. Doing so may slow the spread of the virus for a few days, “because the virus is likely to spread around the world and could infect people in Europe or elsewhere, who could then bring the virus 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 wastewater sampling could help, but testing takes time.

“I think we should be careful about the extent to which this data can really affect our ability to respond,” he said.

(This article is based on a Reuters report.)