"KJ Seung, an infectious disease expert and chief of strategy and policy for the nonprofit Partners in Health’s Massachusetts COVID response, said the study was a reminder of the risk of indoor transmission as many nations hunker down for the winter. The official definition of a (“close contact”) — 15 minutes, within 6 feet — isn’t foolproof...Linsey Marr, a civil and environmental engineering professor at Virginia Tech who studies the transmission of viruses in the air, said the five-minute window in which the student, identified in the study as (“A,”) was infected was notable because the droplet was large enough to carry a viral load, but small enough to travel 20 feet through the air...". source & link: sfgate.com/news
