Population Surveillance of Respiratory Viral Diseases among Arrivals at National Airports and Seaports in the Republic of Korea, February-September 2025.

Objectives: This surveillance report evaluated a pilot program initiated on February 17, 2025, to screen travelers for respiratory tract infections at airports and seaports in the Republic of Korea. We aimed to describe program implementation and respiratory pathogen detection and assessed implications for strengthening national communicable disease surveillance at points of entry. Methods: Screening was offered to the arriving travelers with fever or respiratory symptoms, who had no epidemiological links to the Class 1 quarantinable infectious disease, and participation was voluntary. From February to September 2025, quarantine officers collected nasopharyngeal and oropharyngeal swabs or supervised self-collection, at seven points of entry. Ten respiratory pathogens were tested using real-time reverse transcription polymerase chain reaction. Results: Among 686 symptomatic travelers, 89 (13.0%) underwent respiratory pathogen testing, of whom 46 (51.7%) tested positive for at least one pathogen. A total of 51 (57.3%) respiratory pathogens were detected, including co-infections. Severe acute respiratory syndrome coronavirus 2 (n=17, 33.3%) and influenza A virus (n=13, 25.5%) were the most common, followed by influenza B virus (n=2, 3.9%) and five other respiratory viruses. The monthly positivity rate increased steadily from June, peaking at 72.2% in August. Among participating quarantine stations, positivity was the highest at Gimhae (76.9%) and Cheongju (100.0%) Airports. Conclusions: Traveler-based respiratory testing can support the detection of imported infectious diseases at points of entry. Expanding the program to all national quarantine stations could facilitate early detection and strengthen respiratory infection surveillance.