In order for there to be "airborne spread," people would have to be able to inhale an infectious dose — not just a few viruses, but enough to make them actually sick — from a "suspended cloud of small, dried droplets," the WHO says. This can happen with measles, which can infect a susceptible person — someone who has not been vaccinated or had the disease — even two hours after an infected person has left the room.
Infectious disease experts haven't seen airborne spread of Ebola, in spite of "extensive studies of the Ebola virus over several decades."
The WHO adds: "Common sense and observation tell us that spread of the virus via coughing or sneezing is rare, if it happens at all."
While it's theoretically possible for someone to become infected through coughing, the WHO's new statement explains why this is highly unlikely.
"Theoretically, wet and bigger droplets from a heavily infected individual, who has respiratory symptoms caused by other conditions or who vomits violently, could transmit the virus – over a short distance – to another nearby person. This could happen when virus-laden heavy droplets are directly propelled by coughing or sneezing (which does not mean airborne transmission) onto the mucus membranes or skin with cuts or abrasions of another person."
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