A team of scientists in the UK are using a new method to determine how long Sars-CoV-2 – the virus that causes COVID-19 – can remain viable in the air. The research will help policy-makers better understand the risk of airborne transmission, and inform strategies to prevent the virus from spreading.
According to The Guardian, researchers have developed an apparatus that can generate tiny particles containing live Sars-CoV-2 virus, and gently levitate them between two electric rings, for as short as a few seconds, or as long as days. The temperature, humidity and UV light intensity of the surrounding air is tightly controlled, and can be manipulated to replicate various real-world scenarios and climates.
“We can effectively mimic a cold, wet British winter – or even a hot, dry summer in Saudi Arabia – to look at how these dramatic differences in environmental conditions affect how long the virus remains infectious while suspended in air,” says Allen Haddrell, the University of Bristol chemist who designed and built the apparatus, known as Celebs.
The team has been using Celebs to test how long mouse coronavirus can remain viable in the air. They have noted a large drop in inactivity after the first 10 minutes, and also that the virus survives much longer at lower temperatures.
As previously reported, airborne transmission is gradually being acknowledged around the world as a major vector for the virus – and possibly the most important one.
Recently released draft guidelines from the US Centers for Disease Control and Prevention (CDC) reflected this. Although the advice was subsequently deleted, it was widely circulated in mainstream media before being yanked from the CDC website, and an update to the page is expected soon.
The revised advice noted that the virus is known to spread through respiratory droplets or small particles, such as those in aerosols, produced when an infected person coughs, sneezes, sings, talks or breathes.
“There is growing evidence that droplets and airborne particles can remain suspended in the air and be breathed in by others, and travel distances beyond 6 feet (183cm) – for example, during choir practice, in restaurants, or in fitness classes,” said the advice.
“In general, indoor environments without good ventilation increase this risk.”