Coronavirus ‘eminently capable’ of spreading through speech: Study
WASHINGTON: Microdroplets generated by speech can remain suspended in the air in an enclosed space for more than 10 minutes, a study published on Wednesday showed, underscoring their likely role in spreading Covid-19.
Researchers at the US National Institute of Diabetes and Digestive and Kidney Diseases had a person loudly repeat the phrase "Stay healthy" for 25 seconds inside a closed box.
A laser projected into the box illuminated droplets, allowing them to be seen and counted.
They stayed in the air for an average of 12 minutes, the study published in the journal Proceedings of the National Academy of Sciences of the United States of America showed.
Taking into account the known concentration of coronavirus in saliva, scientists estimated that each minute of loudly speaking can generate more than 1,000 virus-containing droplets capable of remaining airborne for eight minutes or more in a closed space.
"This direct visualisation demonstrates how normal speech generates airborne droplets that can remain suspended for tens of minutes or longer and are eminently capable of transmitting disease in confined spaces," the researchers concluded.
The same team had observed that speaking less loudly generates fewer droplets, in a work published in the New England Journal of Medicine in April.
If the level of infectiousness of Covid-19 through speech can be confirmed, it could give a scientific boost to recommendations in many countries to wear a face mask and help explain the virus' rapid spread.
Meanwhile, US researchers yesterday reported that over a third of patients treated for Covid-19 in a large New York medical system developed acute kidney injury, and nearly 15 per cent required dialysis.
The study was conducted by a team at Northwell Health, the largest health provider in New York state.
"We found in the first 5,449 patients admitted, 36.6 per cent developed acute kidney injury," said study co-author Kenar Jhaveri, associated chief of nephrology at Hofstra/Northwell in Great Neck, New York, whose findings were published in the journal Kidney International. - AFP, REUTERS