Interestingly, statistical studies allegedly show that smokers don't fare as badly with COVID-19 as non-smokers. Believed to be due to the nicotine, although there may be some other effect.
So I'm trying to breathe in as much "vape" as possible!
Can Vaping Cause Cancer? (I recommend reading this even if you don't smoke.)https://www.quora.com/Can-vaping-cause-cancer/answer/Chris-Price-69
A list of symptoms when quitting tobacco and changing to an ecigarettehttps://www.e-cigarette-forum.com/threads/a-list-of-symptoms-when-quitting-tobacco-and-changing-to-an-ecigarette.3305/
Predicting the black market in e-cigaretteshttps://antithrlies.com/2014/07/04/predicting-the-black-market-in-e-cigarettes/
Electronic cigarettes and heart diseasehttp://www.theverge.com/2017/2/1/14460996/e-cig-vaping-risk-heart-disease-health-jama-study
So the final conclusion appears to be:
1. Vaping does not cause cancer (or extremely unlikely compared with cigarettes).
2. Vaping might trigger unwanted short- or long-term allergic reactions.
3. Vaping might not reduce the risk of heart attack, compared with smoking (but no worse).
4. Not vaping and not smoking at all is less harmful so don't start if you don't already smoke.