CDC to Increase Disease Surveillance of International Travelers

The U.S. Centers for Disease Control and Prevention (CDC) is enhancing its disease tracking system among international travelers, coinciding with the winter virus season.

International travelers returning via four major airports can now opt for testing for over 30 pathogens, supplementing a current program focused on monitoring coronavirus variants, according to a CDC announcement made on November 6.

The expanded testing initiative, which has just begun, will run for three months as a trial program aimed at monitoring winter respiratory diseases such as the seasonal flu. In addition to this, the program will also analyze wastewater originating from airplanes and airport terminals, thereby contributing population-wide data to the information gathered from voluntary nasal swabs.

Sam Scarpino, an epidemiologist at Northeastern University in Boston, noted that this program could identify potential health threats that could become "the next COVID". The new data could also help shape public health guidelines during seasonal virus outbreaks, like the flu, Scarpino added.

Since the fall of 2021, the CDC’s Traveler-Based Genomic Surveillance program has been observing the worldwide development of SARS-CoV-2, the virus behind COVID-19, through voluntary nasal swab PCR testing at international airports. The program identified one of the earliest known cases of a new variant, BA.2.86, in a traveler returning from Japan in August. As of September 2023, over 360,000 travelers have participated in the testing.

The airports engaged in the widened program include San Francisco International Airport — the first U.S. airport to monitor its wastewater for coronavirus variants in the spring — added to that John F. Kennedy International Airport in New York City, Logan International Airport in Boston, and Dulles International Airport situated outside Washington, D.C. Scarpino indicates that PCR testing and wastewater tests "complement each other", with PCR testing offering anonymous information pertaining to individual travelers while wastewater testing displays broader population-scale patterns.

Rachel Poretsky, a microbiologist at the University of Illinois Chicago who oversees local wastewater tracking programs, believes that the expansion is "a really smart way" to detect emerging pathogens entering the U.S through international travel. She hopes to see the CDC extend the program to include more airports and other transport centers like bus and train stations.

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