Covid-19 transmission risks

The International Air Transport Association (IATA) has sought to demonstrate the low incidence of in-flight Covid-19 transmission with an updated tally of published cases.

Since the start of 2020, there have been 44 cases of Covid-19 reported in which transmission is thought to have been associated with a flight journey (inclusive of confirmed, probable, and potential cases).

Over the same period, some 1.2 billion passengers have traveled.

“The risk of a passenger contracting Covid-19 while onboard appears very low.

“With only 44 identified potential cases of flight-related transmission among 1.2 billion travelers, that’s one case for every 27 million travelers.

“We recognize that this may be an underestimate but even if 90 percent of the cases were unreported, it would be one case for every 2.7 million travelers.

“We think these figures are extremely reassuring. 

“Furthermore, the vast majority of published cases occurred before the wearing of face coverings inflight became widespread,” said David Powell, IATA medical advisor.

New insight into why the numbers are so low has come from the joint publication by Airbus, Boeing, and Embraer of separate computational fluid dynamics research conducted by each manufacturer in their aircraft.

While methodologies differed slightly, each detailed simulation confirmed that aircraft airflow systems do control the movement of particles in the cabin, limiting the spread of viruses. Data from the simulations yielded similar results:

  • Aircraft airflow systems, High-Efficiency Particulate Air (HEPA) filters, the natural barrier of the seatback, the downward flow of air, and high rates of air exchange efficiently reduce the risk of disease transmission on board in normal times.
  • The addition of mask-wearing amid pandemic concerns adds a further and significant extra layer of protection, which makes being seated nearby in an aircraft cabin safer than most other indoor environments.

IATA’s data collection, and the results of the separate simulations, align with the low numbers reported in a recently published peer-reviewed study by Freedman and Wilder-Smith in the Journal of Travel Medicine.

Although there is no way to establish an exact tally of possible flight-associated cases, IATA’s outreach to airlines and public health authorities combined with a thorough review of available literature has not yielded any indication that onboard transmission is in any way common or widespread.

Further, the Freedman/Wilder-Smith study points to the efficacy of mask-wearing in further reducing risk.

“ICAO’s comprehensive guidance for safe air travel amid the Covid-19 crisis relies on multiple layers of protection, which involve the airports as well as the aircraft.

“Mask-wearing is one of the most visible.

“But managed queuing, contactless processing, reduced movement in the cabin, and simplified onboard services are among the multiple measures the aviation industry is taking to keep flying safely.

“And this is on top of the fact that airflow systems are designed to avoid the spread of disease with high airflow rates and air exchange rates and highly effective filtration of any recycled air,” concluded Powell.