The International Air Transport Association (IATA) demonstrated the low incidence of inflight COVID-19 transmission with an updated tally of published cases on Thursday.
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 travelled.
“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,” Dr. David Powell, IATA’s Medical Advisor said.
Dr. Powell said that IATA recognises that this may be an underestimate but even if 90% of the cases were un-reported, 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,” he said.
IATA said 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 (CFD) 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, it said.
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 in close proximity 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, IATA said that the Freedman/Wilder-Smith study points to the efficacy of mask-wearing in further reducing risk.
Layered Approach of Preventive Measures
Mask-wearing on board was recommended by IATA in June and is a common requirement on most airlines since the subsequent publication and implementation of the Takeoff Guidance by the International Civil Aviation Organization (ICAO).
This guidance adds multiple layers of protection on top of the airflow systems which already ensure a safe cabin environment with very low risks of inflight transmission of disease.
“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 safe. And this is on top of the fact that airflow systems are designed to avoid the spread of disease with high air flow rates and air exchange rates, and highly effective filtration of any recycled air,” said Dr. Powell.
Aircraft designs add a further layer of protection. They include:
- Limited face-to-face interactions as passengers face forward and move about very little
- The effect of the seat-back acting as a physical barrier to air movement from one row to another
- The minimization of forward-aft flow of air, with a segmented flow design which is directed generally downward from ceiling to floor
- The high rate of fresh air coming into the cabin. Air is exchanged 20-30 times per hour on board most aircraft, which compares very favorably with the average office space (average 2-3 times per hour) or schools (average 10-15 times per hour).
- The use of HEPA filters which have more than 99.9% bacteria/virus removal efficiency rate ensuring that the air supply entering the cabin is not a pathway for introducing microbes.