COVID-19 is Airborne, Acknowledges US CDC

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A COVID-19 infected person produces aerosols when they exhale or talk, and these are immediately inhaled by those who are in the vicinity at a “short-range”. 

Covid 19

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There’s growing evidence that the transmission of SARS-CoV-2 is ‘airborne’  and its aerosols remain suspended in the air and expose individuals at distances beyond 2 m from an infected person to novel COVID-19 infection, a new study published in the medical journal The Lancet said Friday.  In July 2020, as the coronavirus rapidly spread like wildfire, as many as 200 scientists published a statement calling for international bodies including WHO to recognize the potential for airborne spread of COVID-19. There were concerns that people “would not be fully protected” by adhering to the recommended health safety protocols, which predominantly at the time was ‘washing hands’.

By October 2020, the US CDC found that the COVID-19 infection was most likely occurring from airborne exposure to the SARS-CoV-2, and the common route of transmission was between a healthy person and a covid positive individual more than 2 m apart or enclosed spaces with poor ventilation with exposure within 30 minutes. 

Medical experts now have "increasing evidence" from millions of cases of confirmed COVID-19 respiratory infection that the pathogen spreads from airborne transmission. ‘Attempts to reduce COVID-19 spread should focus on tackling airborne transmission,’ said the new research. It continued, the airborne transmission of the virus is considered to be “primary route” for its circulation. Scientists from universities of Leicester, Edinburgh Napier and Hong Kong, Virginia Tech, NHS Lanarkshire said that it is now clear that SARS-CoV-2 transmitted between people at close range through inhalation rather than through surfaces. 

[Credit: NCBI journal]

But what is ‘airborne’? 

Scientists in The Lancet study said that there was confusion in physical behaviour and understanding the difference between “droplet” and “airborne”. “What is important to know is that if a person can inhale particles, irrespective of size, they are breathing aerosols." While the aerosols are much more concentrated at short range, they also travel at longer range.

A SARS-CoV-2 infected person produces aerosols when they exhale or talk, and these are immediately inhaled by those who are in the vicinity at a “short-range” [It is to note that the social distancing protocol reduces the range making the aerosols travel to longer distance, thus minimising the chances of virus contraction]. Experts describe the ‘short range’ for airborne transmission as less than 1 meter. They identified 'silent transmission' when patients were not coughing or sneezing but speaking. This accounts for 40 percent of total infections. 

Experts identified at least 10 lines of evidence of the airborne route of coronavirus. Six experts from UK, USA, and Canada, including Jose-Luis Jimenez, a chemist at Cooperative Institute for Research in Environmental Sciences (CIRES) and the University of Colorado Boulder said “the evidence supporting airborne transmission is overwhelming, and evidence supporting large droplet transmission is almost ‘non-existent’” . 

“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”—medical scientists said in The Lancet study. 

So how can we curb ‘airborne transmission’ of coronavirus?

Scientists advise that the key control measure to curb airborne transmission of coronavirus is 'reducing direct contact'. It is important to maintain social distancing of 6 feet, the aerosols however can travel up 26 feet in just a few seconds. “6-foot guidance is based on an oversimplified scenario that looks at how virus is transmitted by either large or small airborne droplets without accounting for other factors. Transmission is more complex,” scientists from Oxford and Massachusetts Institute of Technology suggest. So, therefore, this is where good quality face-covering plays a role in reducing the risk of aerosol inhalation.

There needs to be a special focus on preventing infection transmission indoors, particularly removal of the virus-laden droplets from indoor air by ventilation.  This includes increased ventilation rate, using natural ventilation, avoiding air recirculation, avoiding staying in another person’s direct airflow, and minimizing the number of people sharing the same environment.

Hospitals must have adequate ventilation and residents must-try techniques of ‘opening windows’ for outdoor air to circulate. The use of masks within droplet distance remains primary respiratory hygiene. As per the US National Institute of Health, at the time when covid spread in China, airborne transmission “had not been determined”. Numerous cruise ships where thousands of people onboard were infected in limited space were potentially due to airborne transmission. 

(Image Credit: unsplash/representative image)

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