(Daily News Scan - DNS English) Could Corona virus be Airborne?
Covid-19 has been a topic of serious concern around the world. Scientists and researchers are working hard to find its cure, symptoms, transmission, presence on different surfaces and the agents of its transmission. Recently, The New York Times has reported that 239 scientists from 32 countries have consented on that the virus causing Covid-19 can remain airborne for a period of time and thus transmit itself. The scientists have presented a paper named ‘It is Time to Address Airborne Transmission of Covid-19’ which will soon be published in a scientific journal.
In this DNS we will learn about what the scientists have to say about the presence of virus of Covid -19 and its presence in the air.
The scientists from 239 countries have researched about the virus causing Covid-19 and its presence in the air. They have outlined the evidence showing that smaller particles present in the air can infect people. They are calling for the agency i.e. WHO to revise its recommendation.
A respiratory infection such as Covid-19 is transmitted
through droplets of different sizes. When the droplets particles are larger than
5-10 microns in diameter, they are referred to as respiratory droplets. If they
are smaller than 5 microns in diameter, they are referred to as droplet nuclei.
The WHO states-“According to current evidence, Covid-19 virus is primarily
transmitted between people through respiratory droplets and contact routes.”
In WHO’s view, droplets containing the virus, produced during speech, coughing,
sneezing etc., are larger than 5-10 microns in diameter, which due to gravity
fall to the ground after travelling less than 1 metre. The 239 scientists, on
the other hand, are citing evidence that the virus can be present in droplet
nuclei (less than 5 microns in diameter) that do travel distances longer than 1
metre, and can remain in the air for a longer time period.
If the scientists are correct and the evidence provided by them are established,
it will mean that the risk of transmission is higher than previously thought.
According to WHO, airborne transmission may be possible in specific circumstances and settings. These include settings in which procedures that generate aerosols are performed; endotracheal intubation; bronchoscopy; open suctioning; administration of nebulised treatment; manual ventilation before intubation; turning a patient to the prone position; disconnecting a patient from the ventilator; non-invasive positive-pressure ventilation; tracheostomy; and cardiopulmonary resuscitation.
Referring to the NYT report, the WHO has stated that “initial findings need to be interpreted carefully.” If the evidence being cited has to be examined, researchers will look at the specific settings in which the virus was found airborne, the duration for which the virus was found staying in the air, and, most importantly, whether the virus continues to be infectious throughout this duration.
There have been various studies done and evidences collected by the researchers before claiming that coronavirus can be an airborne transmission. One of the first studies which was published in Nature, was conducted in Renmin Hospital and Wuchang Fangcang Field Hospital in Wuhan. It investigated the aerodynamic nature of the virus SARS-CoV-2 by measuring its viral RNA in aerosols.
The study found that the concentration of the virus in aerosols detected in isolation wards and ventilated patient rooms was “very low”, but it was “higher in the toilet areas used by the patients”. “Levels of airborne SARS-CoV-2 RNA in the most public areas was undetectable, except in two areas that were prone to crowding,” the study stated.
In April, a correspondence published on NEJM by researchers from the US National Institute of Allergy and Infectious Diseases evaluated the stability of SARS-CoV-2 (and SARS-CoV-1, which causes SARS) in aerosols and on different surfaces. It found that SARS-CoV-2 “remained viable in aerosols” throughout the duration of the experiment that lasted for three hours. The results indicated that aerosol and fomite transmission of SARS-CoV-2 is plausible since the virus can remain viable and infectious in aerosols for hours.
WHO, disagreed with the findings of NEJM article, saying that the finding of COVID-19 virus in aerosol particles up to 3 hours does not reflect a clinical setting in which aerosol-generating procedures are performed—that is, this was an experimentally induced aerosol-generating procedure.
In May, the US Centers for Disease Control and Prevention (CDC), published a study titled “High SARS-CoV-2 Attack Rate Following Exposure at a Choir Practice”. The researchers, who studied “super spreading events”, found that following 2.5-hour choir practice attended by 61 persons, including a symptomatic index patient, 32 confirmed and 20 probable secondary Covid-19 cases occurred; three patients were hospitalised, and two died.
The study noted that “the act of singing” might have contributed to “transmission through the emission of aerosols, which is affected by the loudness of vocalization”. Certain people, are super emitters, who release more aerosol particles during speech than others, might have contributed to this and previously reported COVID-19 super spreading events.
Aerosol emission during speech has been correlated with loudness of vocalization, and certain persons, who release an order of magnitude more particles than their peers, have been referred to as super emitters and have been hypothesized to contribute to superspeading events. Members had an intense and prolonged exposure, singing while sitting 6–10 inches from one another, possibly emitting aerosols.”
If the claims made by the scientists are established then wearing a mask will become more essential than ever. It might be possible that N-95 masks, which are used by clinicians in hospital settings, could now be recommended to prevent aerosol transmission, subject to availability, and depending on the health condition of a person.
