If you've been itching to travel again, you likely also are wondering when will it be safe to fly. A research letter reviewing the effect of COVID-19 infected passengers on a flight in March attempted to answer that question. The case series, published in JAMA on August 18, is based on the experiences of 102 passengers who were on a flight from Tel Aviv, Israel, to Frankfurt, Germany.

Twenty-four passengers on the flight were from the same tourist group. A week before their flight, they were unknowingly exposed to someone who later tested positive for COVID-19. Before the flight, none of the travelers seemed sick. The researchers said of the 4 hour and 40 minute flight, “No measures to prevent transmission (e.g., wearing masks) had been applied.”

The researchers tested the tourist group when they landed in Germany and found that of the 24, 7 were positive. Four people got sick during the flight, 2 would go on to develop symptoms and 1, although positive, was asymptomatic. The group, which made up a quarter of the passengers, exposed the other passengers when on the plane. The research team was able to follow up with most of the other passengers and found 2 confirmed COVID-19 cases that they attributed to the tourist group, although they weren’t sure infection happened on the plane. “These transmissions may have also occurred before or after the flight,” they wrote. The researchers mapped out the plane’s seating chart and found that the 2 passengers who went on to develop COVID-19 were sitting no more than 2 rows away from the infected tourists.

In another “what happens-in-the-air” study, Arnold Barnett, PhD, a professor of statistics at MIT released his estimates for the chances of getting COVID-19 on a plane. He found that the odds were “1 in 4,300 for full flights and 1 in 7,700 when middle seats are kept empty.” Dr. Barnett also tried to calculate the risk of death from a plane-transmitted COVID-19 infection. He found that anywhere from 1 in 400,000 to 1 in 600,000 passengers would die. His paper has yet to be peer-reviewed.

Like any activity, flying during the pandemic is risky, but it seems that it is a calculated risk. Dr. Barnett did find that the risk went down when the plane wasn’t at full capacity.