Monday 8 February 2021

COVID-19 and vaping

In my fifteen years reading and writing about junk science, I have occasionally wondered if the day would come when a relative risk of 1% would be considered newsworthy. That day has finally arrived thanks to the Telegraph...
Vapers with Covid-19 up to 20 per cent more likely to transmit it than infected non-smoker, study finds 

Vapers who have Covid-19 are up to 20 per cent more likely to transmit the virus, spreading it in clouds of smoke, a study has found.

Bystanders exposed to low intensity expirations from an infectious vaper in indoor spaces, such as houses and restaurants, are one per cent more likely to catch coronavirus, researchers from Italy, Mexico and New Zealand found.

The study in question is a pre-print by Sussman et al. It's not an epidemiological study and it doesn't attempt to measure risk. Instead, it measures air exhalation and respiratory droplets in indoor places. It essentially tries to answer the question of how much more air vapers exhale than non-vapers and whether this has any implications for the spread of SARS-CoV-2. 

The answer is that vapers do exhale a bit more. One per cent more at normal low intensity, rising to 5-17 per cent at high intensity. From this it can be inferred that somebody who has COVID-19 and is vaping would exhale more potentially infectious droplets than someone who is not vaping. 

The authors are careful to point out that this needs to be put in context with other things people might do that would increase the amount of respiratory droplets they exhale. Talking, for example, doubles or triples the amount. Coughing increases it even more.

Unsurprisingly, the Telegraph has not run with the talking angle. The journalist (not Sarah Knapton for once) doesn't inspire confidence in her knowledge of the subject by repeatedly referring to e-cig vapour as 'smoke' and does not explain what the 'up to 20%' [sic] risk is compared with (ie. someone breathing but not speaking, singing, coughing etc.).

The researchers themselves come to a more measured and less sensationalist conclusion:

Risk assessments are essential to provide evidence based support for preventive and mitigating policies that have been proposed and enacted worldwide... Our risk assessment provides valuable information for safety policies in this scenario: low intensity vaping only produces a minuscule (∼1 %) extra contagion risk with respect to the control case scenario of continuous breathing. Safety interventions should consider that abstention from vaping would not produce a noticeable safety improvement, but could generate an undesired level of stress and anxiety under long term confinement. High intensity vaping produces a higher increase of relative risk, but still well below speaking and coughing.

In terms of keeping Covid-safe, they advise keeping a distance of two metres from vapers, as you would with another else.

And that's really all there is to it, but expect the 'vapers spread Covid' meme to circulate as a result of this irresponsible reporting (the Daily Mail has also got in on the act).

On a different note entirely, a bit of housekeeping. Has anyone else found that it takes ages for this blog to fully load up these days? The sidebar, in particular. Blogger made some 'improvements' a few months ago which made writing blog posts more difficult and seemed to slow everything down. I've considered leaving the platform, but I mostly use this blog to link to my articles elsewhere these days and I can't be bothered with the hassle.

I have been remiss in looking at the comments in the last year or so. Apologies for that. I used to get a email with each comment but those dried up ages ago. I have now put the Disqus moderation page in my bookmarks and will make more of an effort to read and reply to you in the future, so do keep them coming.

I mention all this at the bottom of this post because I know only loyal readers will get this far!

No comments: