Thread by @kakape

.@WHO sent out email this morning, dealing with question of airborne spread of #covid19. A few quotes to come. Bottom line: "According to current evidence, COVID-19 virus is transmitted between people through respiratory droplets and contact routes.” who.int/news-room/comm…

@WHO How does droplet transmission work? Being within 1 meter or so of someone who has respiratory syndromes (coughing, sneezing) can expose mucosae (mouth and nose) or conjunctiva (eyes) to infectious droplets (generally considered to be > 5-10 μm in diameter).

@WHO This can be indirect too via so-called fomites. So, transmission of #covid19 "can occur by direct contact with infected people and indirect contact with surfaces in the immediate environment or with objects used on the infected person (e.g. stethoscope or thermometer)"

@WHO Airborne transmission on the other hand usually means the virus is present in droplets that are smaller than 5μm. "They may remain in the air for long periods of time and be transmitted to others over distances greater than 1 m.” So does this happen with #SARSCoV2?

@WHO According to @WHO it may be possible during certain procedures that can produce an aerosol, such as intubation or taking a patient off the ventilator. But other than that, they are skeptical of evidence for airborne transmission.

@WHO A recent @NEJM paper produced #covid19 aerosol using a nebulizer and still found virus in aerosol particles after 3 hours. @WHO: “This is a high-powered machine that does not reflect normal human cough conditions ...does not reflect a clinical setting"

@WHO @NEJM On the other hand, @WHO cites analysis of 75,465 #covid19 patients in China where airborne transmission was not reported. And: "There are reports from settings where symptomatic COVID-19 patients have been admitted and in which no COVID-19 RNA was detected in air samples"

@WHO @NEJM To sum up: "WHO continues to recommend droplet and contact precautions for those people caring for #COVID19 patients and contact and airborne precautions for circumstances and settings in which aerosol generating procedures are performed”.

One addition because people keep asking/tweeting about this: “to date only one study has cultured the #COVID19 virus from a single stool specimen. There have been no reports of faecal−oral transmission of the COVID-19 virus to date.”