The Centers for Disease Control and Prevention is talking to airlines about the possibility of testing for the coronavirus in sewage from planes, the federal agency told NBC News.

Since September 2021, the CDC has been testing international travelers for Covid on a volunteer basis via nasal swabs. The program now includes seven major airports. Expanding that surveillance to include wastewater could allow the CDC to collect more data about emerging variants.

The U.S. has been monitoring for the coronavirus in wastewater since the CDC launched its National Wastewater Surveillance System in September 2020. But that testing mainly involves wastewater from households or buildings, not samples from airports or planes.