Although data are scant, Dr. Rui Pumbal and colleagues tell us that there have been only about 42 confirmed or suspected cases of COVID transmission during air travel in the entire world. By contrast, on high-speed trains in China, there have been more than 2,300 known cases (an overall rate of 0.3% among all passengers).

Air travel is relatively safe because of the configuration of airflow, as shown in Figure 1.

The quality of the cabin air is surprisingly good. The air that enters the plane consists of 50% air from outside and 50% air that is recycled through HEPA filters – the same filters that are used in operating rooms. According to the authors, seat backs provide a partial barrier, and people, especially when they don’t move around, are facing in the same direction, which minimizes the face-to-face transmission of viral particles.