Study: Covid loses '90pc of its infectiousness within five minutes of being airborne'

Coronavirus loses 90 per cent of its infectiousness within five minutes of becoming airborne, a new study has suggested.

Preliminary data from the University of Bristol reveals that in a real world situation the conditions of the air dry out the viral particles.

The team measured how stable SARS-CoV-2 droplets – the virus which causes Covid – are over time, ranging from five seconds to 20 minutes.

“A decrease in infectivity to approximately 10 per cent of the starting value was observable for SARS-CoV-2 over 20 minutes, with a large proportion of the loss occurring within the first 5 minutes after aerosolisation,” the scientists write in the paper.

The findings indicate that the virus does not survive for long outside the warm and damp environment of a host's respiratory system, and loses its potency rapidly in the wild.

The study, which has not yet been published in full or peer-reviewed, shows that in air with 50 per cent humidity, akin to that circulated in large buildings, there is a “near-instant loss of infectivity in 50 to 60 per cent of the virus”.

At much higher humidity, the droplet does not dry out instantly and remains fluid for longer, which means the virus remains stable and infectious for two minutes.

However, even under these favourable conditions the virus loses 90 per cent of its infectiousness after ten minutes.

“It means that if I’m meeting friends for lunch in a pub today, the primary [risk] is likely to be me transmitting it to my friends, or my friends transmitting it to me, rather than it being transmitted from someone on the other side of the room,” Prof Jonathan Reid, the study’s lead author from the University of Bristol, told The Guardian. ...