Vaping and COVID

Q: Did you see this study saying vaping makes you five times more likely to get COVID?

A: Yes, but it’s not in the news, so it doesn’t count for StatsChat

Q: Newshub covered it.

A: Ok. Not entirely convinced

Q: They did a survey and they did lots of reweighting, the way you like. And said exactly what questions they asked.

A: Yes…

Q: So it’s not dodgy like the paper about heartburn drugs

A:  No, not like that.

Q: What’s your problem, then

A: The first problem is the proportion of people with COVID tests. No, actually the first problem is that COVID is so rare that this isn’t a reliable way to estimate proportions, and the second problem is that getting a test depended on a lot of other factors back then.  The third problem is the proportion of people with COVID tests

Q: Which is?

A:  Over 5% of people 13-17 and over 10% of people 21-24. By May 14, when the total cumulative number of tests in the whole US was only about 5% of the population — and you’d expect lower testing rates in younger people.

Q: Where are those numbers in the paper?

A: It’s a combination of the user and non-user columns in Table 1, using the proportions in the Supplementary Material. Which, again, the authors should get credit for providing.  What they call “COVID-related symptoms” are also very high: 14% of non-vapers and 26% of vapers reported having the symptoms right at the time they were surveyed.

Q: You’d think we would know if vaping increased these symptoms that much, separately from COVID. But if they oversampled people at high risk of COVID, it should at least be comparable across their survey

A: They did separate surveys for users and non-users of e-cigarettes, so that’s not actually obvious.

Q: But weighting?

A: Yes, but that doesn’t help as much with matching the surveys to each other, especially as they don’t have separate census totals for vapers and non-vapers.  In particular, in mid-May COVID was concentrated in relatively small areas of the US, and it would have been more valuable to make sure the locations matched up.

Q: But we know that smokers are at higher risk of catching the coronavirus, so this just confirms that.

A: Surprisingly, no.  Smokers don’t seem to be at higher risk of getting infection — and I guarantee that it’s not because no-one tried to show they were.  They may be at higher risk of getting seriously sick if they are infected, but even that’s not as clear as you’d expect.

Q: So should we believe this?

A: It’s not as simple as that.  This study does provide some evidence, but not as strong evidence as the researchers think. It certainly isn’t strong enough evidence to change policy on the regulation of e-cigarettes; whatever  you believed about that before seeing this study, you should believe about the same afterwards. And you probably do — it’s not a topic where people are noted for changing their minds.