Asymptomatic Transmission of SARS-CoV-2 on Flights

Angie Szumlinski Studies

On March 31, 2020, there was a study of 310 passengers who boarded an evacuation flight from Milan, Italy, to South Korea. This evacuation flight was conducted under strict infection control procedures by the Korea Centers for Disease Control and Prevention (KCDC), based on the guidelines of the World Health Organization (WHO). When the passengers arrived at the Milan airport, medical staff performed physical examinations, medical interviews, and body temperature checks outside the airport before boarding, and 11 symptomatic passengers were removed from the flight.

Medical staff dispatched from KCDC were trained in infection control under the guidance of the KCDC and complied with the COVID-19 infection protocol, which was based on WHO guidelines. N95 respirators were provided and passengers were kept 1 m apart for physical distancing during preboarding. Most passengers wore the N95 respirators except at mealtimes and when using the toilet during the flight. After an 11-hour flight, 299 asymptomatic passengers arrived in South Korea and were immediately quarantined for 2 weeks at a government quarantine facility in which the passengers were completely isolated from one another. Despite these precautions, one passenger tested positive for Covid-19 on quarantine day 14, and researchers deemed that it was highly likely she became infected on the flight; 6 passengers had tested positive on the first day of quarantine, one of which was only three rows away from the later-positive passenger.

This study was one of the earliest to assess the asymptomatic transmission of COVID-19 on an aircraft. Previous studies of inflight transmission of other respiratory infectious diseases such as influenza and severe acute respiratory syndrome revealed that sitting near a person with respiratory infectious disease is a major risk factor for transmission. Further attention is warranted to reduce the transmission of COVID-19 on aircraft.

Stay the course, stay strong, stay well, mask up and stay tuned!