Airborne COVID-19 infection is definitely possible under certain conditions. Chances of picking up SARS-CoV-2 or the novel coronavirus from air is directly related to the number of positive cases in the room, their symptomatic status and duration of the exposure in closed room experiments conducted in various hospitals in Hyderabad and Mohali (Punjab) by the CSIR-Centre for Cellular & Molecular Biology (CCMB).
In 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. The study, published in the preprint server medRxiv, recommends that the demarcation of hospital areas into COVID and non-COVID areas is a successful strategy to prevent cross infections.
And, in neutral environmental conditions, the virus does not seem to spread farther away from the patients, especially if they are asymptomatic, giving objective evidence for effectiveness of physical distancing in curbing the spread of the epidemic, it said.
“We have analysed the air samples collected from various enclosures in hospitals in the two cities and performed closed room experiments with COVID-19 positive individuals. We had 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,” informed CCMB Director Rakesh Mishra on Tuesday.
Early detection and isolation
The study shows that early detection and isolation of positive individuals helps in preventing infection of other family members in a home setting. Viral particles could be detected in air especially in closed rooms where COVID positive individuals had spent longer periods, even after two hours of their exit from the room and at distances greater than two meters as well.
Dr. Mishra has said considering the increased public mobility and interactions and based on the study, wearing a mask in public or crowded places should be made mandatory. Using masks significantly decreases the viral load released by a COVID positive individual and the spread of the pandemic, to a large extent, can be attributed to people having unprotected verbal interaction from close quarters with asymptomatic COVID positive individuals, he pointed out.
The advisory following the study stated that the risk of transmission is very low if both the affected person and unaffected person wear masks.
- Social distancing is a must and a distance of three feet at least, if not six feet should be maintained.
- Spending more time in closed spaces can be risky even if social distancing is maintained as the virus can stay longer in the air in closed rooms not properly ventilated.
- It is also avoidable going to others homes considering the risk of contracting the disease in home environments is likely to be higher.
The advice is to conduct larger gatherings in open and well-ventilated spaces as it carries less risk of infection. Adequate measures should be taken in offices/ schools to facilitate cross ventilation. Exposure to a COVID positive individual for a short duration (< 30 mins) when adequate precautions are being taken does not significantly increase the risk of contracting the disease.
It also means short duration of travel in metros/ local trains or buses is likely to be safe. If one needs to travel longer, the journey may be broken into sub parts to mitigate the risk. For example, if the journey from point ‘A’ to ‘B’ is for an hour, it can be broken down into two journeys of half-hour each better.
Caution while using public toilets
Caution to be exercised while using public toilets as flushing has the potential to generate aerosols which can stay longer in air and virus is known to be excreted in stool. Masks should be always on while using these and if possible, the same toilet should be reused only after half an houror more of last usage. Pictorial instructions should be stuck in the toilets regarding cleaning them after utility. This should be followed by adequate hand hygiene.
For those in home quarantine, the infected person should be isolated in a separate room with a toilet, keeping utility things separately and other family members should preferably wear masks besides ensuring the rest of the house if properly ventilated. Within offices, texting and mailing should be encouraged even if sitting next to each other in the same room. Instead of face to face interactions, mobiles and telephones should be used for verbal communication, the advisory said.