A new study focused on the indoor environment and coronavirus transmission has been undertaken, with data gathered in South Korea. The research is titled “Evidence of Long-Distance Droplet Transmission of SARS-CoV-2 by Direct Air Flow in a Restaurant in Korea”, and published in the Journal of Korean Medical Science. The research examines a transmission event with the coronavirus that took place at a distance of over 6.5 metres (20 feet) in only 5 minutes.
Virologists regard the event as concerning considering the standard close contact definition is 6 feet (2 metres) for 15 minutes. The transmission goes beyond the standard droplet transmission metric. The new incident is a further event that adds weight to the possibility of airborne transmission.
To gather the epidemiological research, virologists undertook personal interviews with those who were at the restaurant. The researchers also reviewed closed-circuit television images, and confirmed movements using smartphone location points.
The inquiry drew upon a system established by the Korea Disease Control and Prevention Agency. This centered on contact tracing technology. This was considered alongside factors like the place in the diner where the exposure happened, plus the air flow direction and the air velocity. Also considered was the physical distances between those involved, together with the movement of people inside the eatery.
The data showed there were three cases of COVID-19 infection identified. Inside the restaurant the maximum airflow velocity was measured as 1.2 metres per second (in terms of the space between the infector and infectee), with the air provided by air conditioning units. The person who became infected was sitting 6.5 metres away from the infector. It was assessed that only five minutes exposure was required. Importantly, there was no direct or indirect contact between the parties.
The inference from the study is that droplet transmission is possible at a distance greater than 2 metres under conditions where there is direct airflow from an infected person. This has implications for contact tracing and preventative measures designed to reduce coronavirus infection spread.
