Coronavirus particles found in air can infect humans, experiments show

Scientists found that the virus could be detected in air around Covid-19 patients


A new study has confirmed the airborne transmission of SARS-CoV-2, concurring with previous studies that suggest that the concentration of the virus RNA is higher in indoor air as compared to outdoor spaces.

The collaborative study was conducted by a group of scientists from Centre for Cellular and Molecular Biology (CCMB), Hyderabad and IMTech, Chandigarh, with hospitals in Hyderabad and Mohali, a CCMB release said in Hyderabad on Tuesday.

The release said 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, it said.

The study confirmed the airborne transmission of SARS-CoV-2, after the scientists analysed the coronavirus' genome content from air samples collected from different areas occupied by COVID-19 patients, including hospitals, closed rooms in which only coronavirus patients spent a short period of time, and houses of home-quarantined COVID-19 patients, it said.

The scientists found that the virus could be frequently detected in air around COVID-19 patients and the positivity rate increased with the number of patients present in the premise.

They 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 study also found viable coronavirus in air that could infect living cells, and these viruses could spread over a long range of distance, it said.

Scientists still suggested wearing face masks to avoid the spread of coronavirus. "Our results show that coronavirus can stay in the air for some time in absence of ventilation in closed spaces. We find that 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," said Shivranjani Moharir, scientist involved in the study.

"Our observations are concurrent with previous studies that suggest that the concentration of SARS-CoV-2 RNA is higher in indoor air as compared to outdoor air; and 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," Moharir said.

"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. This can help refine strategies to control the spread of infections," said Rakesh Mishra, the lead scientist of the work, and Director, Tata Institute for Genetics and Society.

He further said that the air surveillance technique is not just limited to coronavirus but can also be optimised to monitor other air-borne infections. The study was published in the Journal of Aerosol Science.