Overwhelming strong evidence has emerged that the virus which causes COVID-19 is largely airborne and not transmitted through large droplets as assumed earlier, said an expert analysis published in the medical journal Lancet on April 17.
This new evaluation made by six experts has serious implications on public health measures being widely practised around the globe to mitigate the pandemic. According to the experts, there should be no further delay in implementing health measures to protect against this kind of airborne transmission, said a LiveMint report.
If public agencies around the world do not take into account that the SARS-CoV-2 virus, which causes the COVID-19 pandemic is airborne, they are allowing the virus to spread, argued the six experts from the UK, USA and Canada. One of the experts included Jose-Luis Jimenez, a chemist at the Cooperative Institute for Research in Environmental Sciences (CIRES) and the University of Colorado Boulder.
“The evidence supporting airborne transmission is overwhelming, and evidence supporting large droplet transmission is almost non-existent,” Jimenez said, adding that the World Health Organization and other public health agencies should focus on trying to lessen airborne transmission to fight the virus.
The team led by University of Oxford’s Trish Greenhalgh had poured through published research, even highly complex and specialist papers on the dynamics of fluid flows and the isolation of live virus, and came to the conclusion that the evidence the virus is airborne is “extensive and robust”.
They identified ten lines of evidence to support this theory. The one that topped the list was the case of the Skagit Choir outbreak in Washington, in which 53 people got infected from a single infected case. This showed that infections did not happen just by close contact or touching shared surfaces or objects. Also, they found that the SARS-CoV-2 virus was transmitted faster in an indoor setting than outdoors, and that transmission comes down with adequate indoor ventilation.
The team also gave examples of research that had revealed that silent (asymptomatic or presymptomatic) transmission of the virus accounted for at least 40 per cent of all transmission. This silent transmission without coughing or sneezing is a key way COVID-19 has spread around the world, and this supported their assessment that the virus takes the airborne route.
Meanwhile, there is no evidence to support the theory that the virus spreads easily via large droplets which fall and contaminate surfaces. Droplet measures such as handwashing and surface cleaning, while not unimportant, should now be given less weightage than airborne measures, which deal with inhalation of infectious particles suspended in the air.
Further, the team had assessed that if an infectious virus is primarily airborne, people can get infected when they inhale the aerosols that are produced when an infected person exhales, speaks, shouts, sings, or sneezes.
So, to control an airborne virus, the measures to be taken include ventilation, air filtration, limit crowding and the amount of time people spend indoors, besides stressing the importance of wearing masks whenever indoors (even if not within six feet or two meters of others). People should also ensure they wear quality mask that fit properly and healthcare workers and other staff should also be adequately protected with higher-grade PPE when dealing with infectious people.
According to the team, we should not be questioning whether the virus is airborne since the examples of indoor outbreaks around the world are a clear indication that this is the way it is being transmitted. “Once we acknowledge this virus is airborne, we know how to fix it. There are many examples of places that have fared much better by acknowledging this virus is airborne from the start. The world needs to follow their lead as soon as possible,” urged one of the co-authors of the assessment, said LiveMint.