One individual on a poorly ventilated bus in China has been found to have infected nearly two dozen other passengers with the coronavirus, according to new research published in JAMA Internal Medicine.

This particular incident adds to a large body of evidence that points toward the fact that SARS-CoV-2, the virus that causes the coronavirus, also known as COVID-19, can be transmitted via tiny particles that linger in the air—and not only through large respiratory droplets that fall quickly to the ground. 

The study’s authors, who are physicians affiliated with the Chinese Center for Disease Control and Prevention, concluded that “future efforts at prevention and control should consider the potential for airborne spread of COVID-19.”  

The bus passengers were part of a fifty-minute trip to a Buddhist event in the eastern Chinese city of Ningbo in January—before face masks were widely used to protect against the coronavirus.

In all, twenty-three out of sixty-eight passengers were eventually confirmed to be infected.

The researchers believe the asymptomatic coronavirus-positive individual, whose gender was not identified, was likely “patient zero” because he or she recently had been in contact with people from the city of Wuhan, where the coronavirus originated.

After extensive research, the study managed to map out exactly where the other passengers were sitting on the bus. What was notable is that several of the infected individuals were seated well beyond six feet from the source of the virus—making airborne transmission the likely culprit.

The study also noted that the vehicle’s air conditioning simply recirculated the air inside the bus, which likely contributed to the spread of the virus.  

“The investigations suggest that, in closed environments with air recirculation, SARS-CoV-2 is a highly transmissible pathogen,” the study’s authors wrote.  

“Our finding of potential airborne transmission has important public health significance.” 

This study comes after the World Health Organization now appearing to be on board with many other medical experts across the world in saying that the airborne spread of the coronavirus is, in fact, possible.  

Airborne transmission is different from droplet transmission, according to the agency, as the former refers to the presence of extremely small particles that can remain in the air for long periods of time and has the potential to be transmitted to others over distances greater than three feet. 

At the beginning of the coronavirus outbreak, both the WHO and the U.S. Centers for Disease Control and Prevention often asserted that individuals need to worry about only two types of transmission: inhaling respiratory droplets from an infected person nearby and touching a contaminated surface and then your eyes, nose, or mouth.  

According to the latest data from Johns Hopkins University, there are more than 25.9 million confirmed cases of coronavirus worldwide, including at least 861,000 related deaths.

Ethen Kim Lieser is a Minneapolis-based Science and Tech Editor who has held posts at Google, The Korea Herald, Lincoln Journal Star, AsianWeek and Arirang TV. Follow or contact him on LinkedIn.  

Image: Reuters