The CDC is expanding its disease surveillance of international travelers

The U.S. Centers for Disease Control and Prevention is expanding how it tracks diseases among international travelers, just in time for the winter virus season.

Travelers returning to four major international airports now have the option to be tested for more than 30 pathogens, building upon a program that tracks coronavirus variants, the CDC announced November 6.

This expanded testing, which has just started, will continue for three months as a pilot program designed to track winter respiratory diseases such as seasonal flu. The program will also screen wastewater from airplanes and airport terminals, adding population-level data to information from voluntary nasal swabs.

This program could catch potential health threats that might be “the next COVID,” says Sam Scarpino, an epidemiologist at Northeastern University in Boston. The new data may also inform public health guidance during outbreaks of seasonal viruses like the flu, he says.

Since fall 2021, the CDC’s Traveler-Based Genomic Surveillance program has tracked the global evolution of SARS-CoV-2, the virus responsible for COVID-19, through voluntary nasal swab PCR testing at international airports. In August, the program picked up one of the first known cases anywhere of a new variant, BA.2.86, in a traveler returning from Japan. More than 360,000 travelers have participated in the testing as of September 2023.

Airports participating in the expanded program include San Francisco International Airport — which became the first U.S. airport to screen its wastewater for coronavirus variants this spring (SN: 5/9/23) — along with John F. Kennedy International Airport in New York City, Logan International Airport in Boston and Dulles International Airport outside Washington, D.C. The PCR and wastewater tests “complement each other,” Scarpino says, as the PCR testing provides anonymous information about individual travelers while the wastewater testing provides broader population-level patterns.

The expanded program is “a really smart way” to look for new pathogens reaching the United States through international travel, says Rachel Poretsky, a microbiologist at the University of Illinois Chicago who directs local wastewater monitoring programs. She’d like to see the CDC expand further to more airports as well as other travel hubs such as bus and train stations.