Chances of catching COVID indoors related to positive cases in the room

Airborne transmission of coronavirus depends on the number of COVID-positive people in a room, because droplets carrying the virus can travel farther in closed spaces, according to a study by India’s Council of Scientific and Industrial Research (CSIR).

There is consistent, strong evidence to prove that the SARS-CoV-2 virus is predominantly spread through the air, according to various international studies. More recent evidence has suggested that the virus can travel up to 10 metres riding on aerosols, which are micro-droplets that come out of the mouth or nose of an infected person.

CSIR conducted the study “to understand air transmission characteristics of SARS-CoV-2 and risks for health care personnel and visitors to hospitals”.

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The researchers analysed air samples collected from several COVID and non-COVID and ICU and non-ICU areas at hospitals in Hyderabad and Mohali and performed closed room experiments with COVID-19 positive individuals.

“Results indicate that the chance of picking up SARS-CoV-2 in the air is directly related to the number of COVID positive cases in the room, their symptomatic status, and the duration of exposure, and that the demarcation of hospital areas into COVID and non-COVID areas is a successful strategy to prevent cross infections,” the study said.

“In neutral environmental conditions, the virus does not seem to spread farther away from the patients, especially if they are asymptomatic, giving an objective evidence for the effectiveness of physical distancing in curbing the spread of the epidemic,” it added.

Indoor transmission of the infection can be reduced if ventilation, especially air circulation, is improved, according to experts. Merely opening windows and doors can cut the risk of transmission.