Whether the coronavirus is airborne or not is a question that is being debated ever since the virus outbreak was first reported two years ago.

A multi-institutional study has again confirmed the airborne transmission of SARS-CoV-2, highlighting the need for masks to reduce the risk of contracting the virus.

“Our results show that the coronavirus can stay in the air for some time in the absence of ventilation in closed spaces,” said Shivranjani Moharir, a scientist involved in the study.

The study was conducted by scientists from CCMB (Centre for Cellular and Molecular Biology, Hyderabad) and IMTech (Institute Of Microbial Technology, Chandigarh) in association with hospitals in with hospitals in Hyderabad and Mohali.

Indoor settings

The positivity rate of finding the virus in air was 75 per cent when two or more Covid-19 patients were present in a room, in contrast to 15.8 per cent when one or no Covid-19 patients occupied the room in these studies.

Moharir said the findings were concurrent with previous studies that suggested that the concentration of SARS-CoV-2 RNA is higher in indoor air as compared to outdoor air.

“In indoor, it is higher in hospital and healthcare settings that host a larger number of Covid-19 patients, as compared to that in community indoor settings,”Shivranjani said.

Refining strategies

Rakesh Mishra, the lead scientist of the work and AcSIR Distinguished Emeritus Professor at CCMB, said that the findings could help refine strategies to control the spread of infections.

“As we are back to conducting in-person activities, air surveillance is a useful means to predict infection potential of a spaces like classrooms, meeting halls,” Mishra, who is also the Director, Tata Institute for Genetics and Society, said.

Mechanism elusive

The exact mechanism of spread of coronavirus SARS-CoV-2 has remained elusive. Earlier thought to spread by surfaces, epidemiologists found that countries that wore masks in the pandemic were affected less severely. However, quantitative evidences that show the infectious coronavirus particles in air was lacking. The multi-institute study now confirmed the airborne transmission nature of the virus.

The findings of the study are published in the Journal of Aerosol Science.

The scientists analysed for the coronavirus’ genome content from air samples collected from different areas occupied by Covid-19 patients. The samples were collected from hospitals, closed rooms in which only Covid-19 patients spent a short period of time, and houses of home-quarantined Covid-19 patients.

The study found that the virus could be frequently detected in air around Covid-19 patients.

“The positivity rate increased with the number of patients present

in the premise. The study found the virus in ICU as well as non-ICU sections of hospitals, suggesting that patients shed the virus in air irrespective of the severity of infection, the team added.