A new study has shown that, at least on intercontinental flights, the difference between illness and prevention of possible infection is crucial in where one sits and who is nearby.
For most in the cabin, the likelihood of infection was less than 3%, the researchers said.
"Passengers should not worry about getting sick from someone who coughs, for example, in five rows," said Vicki Stover Hertzberg, first author of the study and a professor at the Nell Hodgson Woodruff School of Nursing Emory University.
The study does not compare the spread of germs in an airplane, for example a movie theater. So, what is really thin? "The results of this study did not stop me from flying," Hertzberg said.
The World Health Organization says respiratory diseases such as the flu or SARS are primarily transmitted when a sick person sneezes, coughs or speaks, causing sprouting droplets in the air.
What are the actual risks of spreading a respiratory disease on board an aircraft? It depends on whether sick people are on board – and whether you come into contact with them.
Hertzberg and her co-researchers boarded 10 transcontinental flights to find out. The aircraft company Boeing had funded the research, but did not matter, she said.
Above the clouds, Hertzberg and her colleagues tracked passengers in the often crowded economy of single-aisle aircraft.
One flight had 17 empty seats, two flights had only a few empty seats and seven flights were fully occupied. Of a total of 1,540 passengers, only one person was seen to cough moderately. None of the crew members, a total of 41 people, coughed at all.
The researchers observed passengers moving in the cabin and found that half of them did not use the bathroom. In fact, almost 38% of the passengers have never left their seats, while the same share has left their seats only once; 13% left their seats twice and 11% left more often.
Waiting for the toilet to use it or leave it were the most frequent movements of passengers, followed by checking the luggage rack.
On average, the flights lasted 238 minutes, and each crew member had about 67 minutes of contact with passengers. Based on these data, the researchers estimated that a single sick crewmember could infect nearly five passengers per flight.
To underline their findings, Hertzberg and her colleagues collected 229 environmental samples and, after flights, each tested for 18 common respiratory viruses, including various strains of influenza. All samples taken from air and from hard surfaces were tested negative.
The researchers warn that with shorter hops, the freedom of movement of passengers and crew would be much lower, but on longer flights, significantly more movement – so the results can be transferred to either shorter or longer flights.
"We now know so much about what people do in aircraft and for how long," Hertzberg said, although she noted that in their study, data lacked the risk of spreading disease through fomites: lifeless objects or materials that can carry germs, such as clothing
Dr. Marta Feldmesser, director of infectious disease at Lenox Hill Hospital, New York, said the methodology for the new study was "excellent," but research was limited.
The study can not experience the effects of air flow within an aircraft and before or after the flight, such as waiting at an airport, said surveyor, who was not involved in the research.
Another problem was that "almost no passengers or crew" were ill on the 10 flights examined. This was fortunate for the travelers, but less so for the researchers who had no opportunity to study virus levels in the air or on surfaces.
Still, Surveyor said: Basic hand hygiene is important.
"People should keep their hands as clean as possible and avoid touching their faces," she advised. The transmission rate of 80% or more among the economy passengers who actually rubbed elbows "should remind people to take care of others and reschedule travel either in the event of illness or take additional measures to prevent the transmission" , she said. Safety includes wearing a mask or taking cough syrup.
After all, one person's mild illness may be another person's serious illness, added Surgeon.
Hertzberg agreed that travelers should always practice good hand hygiene in an airplane, she said, "and keep your hands away from your face." If you are ill, use a good etiquette: "Cough or sneeze you down 'in the crook of your arm.'