NEW DELHI: Scientists in India have found the prevalence of coronavirus in the air from hospitals and the closed rooms occupied by Covid-19 patients indicating that demarcation of hospital areas into COVID and non-COVID areas is a successful strategy to prevent cross infections.
A study by scientists at the CSIR at the Centre for Cellular & Molecular Biology (CCMB) indicates that the chance of picking up SARS-CoV-2 in the air is directly related to a 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.
To understand air transmission characteristics of SARS-CoV-2 and risks for health care personnel and visitors to hospitals, CCMB analyzed air samples collected from various enclosures in hospitals in Hyderabad and Mohali and performed closed room experiments with COVID-19 positive individuals.
"We collected 64 air samples from COVID and non-COVID areas of various hospitals and 17 samples from closed rooms occupied by COVID patients. Four samples from COVID care areas were positive for SARS-CoV-2 with no obvious predilection towards ICU/non-ICU areas in the hospital samples," said authors of the study published in preprint server medRxiv
They further said that in the closed room experiments, where one or more COVID-19 patients spent a short duration of time, one sample -- collected immediately after the departure of three symptomatic patients from the room -- was positive.
"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.
In the initial phases of the pandemic, the transmission of SARS-CoV-2 was largely thought to be through contact and droplet spread. However, studies reporting transmission among physically distanced individuals in closed spaces with air conditioning and the fact that the viral spread could not be effectively curbed in spite of strict lockdowns in various countries of the world raised the possibility of its airborne transmission.
In the study, from the air samples collected in hospitals, viruses could be detected from various COVID care areas with no specific predilection towards ICU/ non-ICU areas.
"The virus could not be detected in any of the non-COVID areas, providing objective evidence that the strategy of separating hospital premises into COVID and non-COVID care areas is effective. The positivity rate was found to be higher when the number of COVID patients was higher in the room, a finding concordant with results of closed room experiments as well," it further said.
A point to be highlighted from the hospital experiments was that in 3/4 samples which were positive, the sampler was at least 10 feet away from the nearest patient. As there is no record of events that occurred in the sampling area before the sample collection