Is novel Coronavirus airborne and if so what are the consequences?
There had been two media reports in the New York Times in the last 3 days (1 and 2) and based on that the Indian Express ran a story as well. Now that many news stories quote WHO as acknowledging chances that COVID-19 be airborne after all. Erroneously admitting error that is not committed for political correctness is common among scientists under pressure; while Galileo deliberately lied to escape Christian persecution, Darwin ‘corrected’ later editions of his Origin of Species with politically right but scientifically wrong statements.
Widely covered in media, the key publication every news sources is pointing to is https://academic.oup.com/cid/article/doi/10.1093/cid/ciaa939/5867798
However, there are several issues with this article:
- It is a commentary written by two scientists with signatures of “239 Experts from 32 countries” (while media overemphasize on 239 experts from 32 countries, such adjectives are meaningless in science, scientific consensus has nothing to do with these experts or their signature campaign other than high-quality reproducible data).
- No data presented in the paper. As of now data is deficient and criticising WHO for policy change based on conjectures makes no sense to me.
- We already knew SARS Cov-2 can spread by speech (PNAS article here), so the article adds little to what is already known. The new article is rather a clever play with words, aerosol vs airborne
- Article generalizes several viral diseases and says: “There is every reason to expect that SARS-CoV-2 behaves similarly, and that transmission via airborne microdroplets”
- The article refers to fine aerosol droplets as airborne, which is technically incorrect. Airborne particles are usually powder/dry while aerosol is wet/droplets.
Does such a commentary article require media attention? Why did NYT run a story? I would call this a textbook example of bad journalism. Without high-quality reproducible data, jumping to conclusion and criticising policy think-tanks is not a good practice. By doing so NYT and other news media silently fell prey for strategies of signature campaigners with ulterior political motives.
Aerosol and airborne are two different things, lets us consider the facts. The term ‘aerosol’ refers to superfine respiratory droplets which are mostly water. How fine? No consensus. As per CDC and WHO, <5 µm in diameter (superfine) is aerosol (also called “droplet nuclei”) that can travel more than 1 meter, while >5 µm (coarse) are called droplets, that falls within 1 meter from the source due to gravity. This NEJM paper confirms Cov-2 can remain suspended in the air for up to half an hour, while on plastic it can maintain virulence up to 72 hours. Can aerosol be naturally produced by a human? Yes, there are several lines of evidence that aerosol is produced while sneezing, coughing and even while speaking at a high voice. So arguments that aerosols can only be produced by mechanistic ways as part of surgical procedures don't have scientific rigour.
On the other hand, the term ‘airborne’ refers to superfine respiratory particles, mostly in dry, powder form <5 µm in diameter. It stays in the air much longer (even days) and carries around via wind. Examples of airborne diseases include Measles and Chickenpox.
Conjectures set aside, no, we have insufficient evidence to conclude that the novel Coronavirus is airborne like measles or chickenpox. However, absence of evidence doesn’t mean evidence of absence. It is always better to prepare for the worst-case scenario.
What if Cov-2 is indeed airborne, what are the potential consequences? Physical distancing would be more important than ever. We would need to practice more vigorous physical distancing and 2-meter distance may be inadequate. Airborne would also mean cotton masks won’t much help to prevent transmission. We would need a mask with much smaller pore-size (less than 300 nm) like N95 or reusable microfiber cloth mask. Home-made reusable microfiber masks are still my recommendation, I have created a detailed video on this earlier. My earlier videos covered several other mask-related topics, including how often and how to properly wash reusable fabric masks, why not to use masks with valves, and why wearing masks does not lead to hypercapnia or hypoxia. If airborne transmission of COVID-19 is established, masks might be needed for any indoor spaces even when no one is around. Another consequence would be that we should avoid indoor spaces, including shops, elevators, office spaces, public transportations etc. Also, avoid any gathering where people speak/sing like a church choir. A paper in Nature concluded amplitude (loudness) of speech is directly correlated with the amount of aerosol produced. We should also avoid recirculating air-conditioning; instead, open windows to ensure proper ventilation. this applies only for office spaces or shopping centres; at home, recirculating air is fine.
At this point, let common-sense (science) prevail. Travel only in case of absolute necessity, wear masks indoors and public places. If you are planning to wear masks day long, ensure to go out to open spaces/parks to inhale fresh air once every two hours.
What we know about flattening the curve so far? Newer research indicates that a vast majority of infection might be through asymptomatic carriers. A quarter of the world’s population is at high risk of COVID-19. The risk is exceptionally high if you are obese/bald/has asthma/has lower immunity. We also know that immune boosters/ herbal supplements/ exercise doesn’t work. In addition, herd immunity is meaningless for life-threatening diseases like COVID-19. Countries that flattened the curve and are mostly out of COVID-19 trusted science than politics. Examples include Iceland, Germany, Cuba, China, Finland. A commonality in these countries is that they religiously followed lockdown and stay at home orders. In addition, wearing masks and practising physical distancing had imbibed into cultural etiquette in these countries.
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