Since the beginning of the COVID-19 pandemic, many have speculated that vaping could increase the risk of getting COVID-19 and experiencing more severe outcomes from the disease. The claims were grounded in little to no evidence, and only a small amount has emerged since.
The authors of a California study claimed that their survey showed young vapers were five to seven times more likely than never vapers to test positive. It received a massive amount of media coverage. It also received scathing criticism and calls for retraction from longtime researchers in the field who cited multiple methodological issues.
A large Icelandic study reported that the proportion of e-cigarette users was lower among patients with COVID-19 than in the general population of Iceland and that patients using e-cigarettes did not have more severe symptoms than other patients.
A UK study found, "There were no differences in diagnosed/suspected Covid-19 between never, current and ex-vapers".
A large Mayo Clinic study found that "patients who used only e-cigarettes were not more likely to have a COVID-19 diagnosis".
A UK study found, "People who only vape were more likely to test positive for COVID-19 than non-smokers. This was only found on one other occasion since 14 March 2021."
Disease outcomes were not analyzed in either study.
Another Mayo Clinic study concluded: "Vapers experience higher frequency of covid-19 related symptoms when compared with age and gender matched non-vapers". The study was limited, however, by an inability to determine the frequency or duration of use and by a rarity of severe disease.
An English study stated: "There was no evidence that e-cigarette use was associated with a difference in risk of severe COVID-19, but the estimates were imprecise, encompassing from modest protection to substantial increased risk". It was limited by the fact that vaping status was recorded a median of 23 months prior to the beginning of the study.
A large US study found that e-cigarette use was "not associated with an increased risk of SARS-CoV-2 infection or severe COVID-19 illness".
There is a considerable amount of evidence that current tobacco smoking is associated with a reduced chance of testing positive. Former smokers appear to face more serious outcomes than current or never smokers. Outcome data on current smoking are mixed.
A twitter thread with links to hundreds of studies which report smoking and vaping status data of COVID-19 patients