Strong Proof Covid-19 Mainly Spreads Through Air: Study

New Delhi, 17 April 2021:

Researchers have concluded that there is “consistent” and “strong evidence” to prove the Sars-CoV-2 virus – which causes the coronavirus disease (Covid-19) – is primarily transmitted through air and that this reasoning should alter countries’ mitigation response to the pandemic that has ravaged the world.

Studies have previously indicated that the coronavirus can spread through air, but this is the first such analysis that says the “airborne route is likely to be dominant”.

In the early days of the pandemic, it was believed that the virus is largely transmitted when large droplets, which are exhaled by those infected, settle on surfaces and contaminate them. Months after the first outbreak was reported in China’s Wuhan, around 200 scientists from 32 nations last July wrote to the World Health Organization, saying there is evidence that the coronavirus is airborne.

“The evidence supporting airborne transmission is overwhelming, and evidence supporting large droplet transmission is almost non-existent,” said Jose-Luis Jimenez from the University of Colorado Boulder.

“It is urgent that the World Health Organization and other public health agencies adapt their description of transmission to the scientific evidence so that the focus of mitigation is put on reducing airborne transmission,” Jimenez, one of the authors of the study, told PTI.

The researchers from the UK, the US and Canada reviewed published scientific studies and cited ten reasons as evidence.

Among them is the occurrence of super-spreader events in indoor areas such as choir concerts, cruise ships and care homes, they said. These instances show patterns that are not explained by droplets or fomites [contaminated objects], suggesting the “dominance of aerosol transmission”, said the analysis published in journal Lancet on Thursday.

Super-spreader events, cases where one person diagnosed with Covid-19 goes to infect several others, are believed to be among the key reasons why Sars-CoV-2 has infected 138 million people the world over.

The cluster of Covid-19 cases aboard the Diamond Princess cruise ship in February last year was one of the first examples of a super-spreader event. At least 700 people on the ship were infected during the voyage and its subsequent quarantine off the Yokohama coast in Japan.

The Lancet study noted the transmission rate of Sars-CoV-2 is higher indoors than outdoors, and that transmission is greatly reduced by indoor ventilation, suggesting that viral particles survive in the air.

According to a study cited in the analysis, silent -- asymptomatic or presymptomatic -- transmission of Sars-CoV-2 from people who are not coughing or sneezing accounts for at least 40%. This, too, indicates that the virus is airborne.Hindustan Times