Airplane passengers must be more careful when travelling as a new report revealed that asymptomatic patients may transmit the infection on airplanes. The fact that they're not showing symptoms does not mean that they are not infectious.

In a study, which was featured in the peer-reviewed Emerging Infections Diseases journal, researchers looked at 310 passengers who were at the evacuation flight, which flew from Milan, Italy to South Korea in March. There were 11 who denied the trip after they showed that they had symptoms of COVID-19. It was a long long 11-hour trip.

The Korea Centers for Disease Control and Prevention (KCDC) ensured that they follow infection control procedures. All the passengers had N95 respirator masks in flight, and they would only take them off if they would be eating or when they are using the restroom. They have also kept the recommended distance of two metres apart during preboarding in compliance with social distancing

When the 299 passengers arrived in Korea, they were all quarantined at a facility provided by the government, and they were isolated from one another for 14 days. Doctors frequently examined them for any symptom indicative of SARS-CoV-2. The first day of their quarantine was April 2 and on the same day, six passengers were found to be positive for COVID-19 and ended in the hospital. Two weeks later, the said passengers no longer exhibited any symptom and were classified as asymptomatic.

One of the things that raised alarm was the case of a woman passenger who tested negative when they deplaned but later tested positive for the virus. She exhibited myalgia, rhinorrhea, and coughing. It was noted that all throughout the flight, she wore an N95 mask, except when she went to the restroom. They later found that the restroom was also used by an asymptomatic carrier. The researchers surmise that the woman might have been infected through indirect contact with an asymptomatic carrier in flight.

Inflight risk
Passengers wearing facemasks at Tianhe Airport in Wuhan. China says all new arrivals will have to prove they don't have coronavirus before boarding incoming flights Photo: AFP / Hector RETAMAL

The study was one of the earliest ones, which made an assessment on the transmission of COVID-19 by asymptomatic patients on a plane. The researchers noted that sitting next to a person suffering from respiratory infectious diseases like SARS and influenza is already a risk factor.