“I achieved a personal milestone in April 2020 when, for the first time, one of my articles was flagged up as fake news on Facebook”

Christopher Snowdon:

Since back then Big Tech’s fact-checkers were still describing claims about SARS-CoV-2 being airborne and face masks preventing infection as ‘misleading’, a fake-news flag was something of a badge of honour. And, as with those claims, the ‘disputed’ information in my article has been borne out by the evidence.

After a brief burst of incredulous coverage in the spring of 2020, the media soon lost interest in the hypothesis that smokers are less likely to get Covid-19, but dozens of studies have been quietly published in the past two-and-a-half years which confirm it. I have been listing them on my blog and last week added the hundredth study. It seems a good time to stop. By any reasonable standard, the jury is in.

Of the 100 studies from around the world, 87 of them show a statistically significant reduction in SARS-CoV-2 infection risk among current smokers as compared to non-smokers. Seven of them found no statistically significant association either way. Two of them found mixed results. Four of them found a positive association between smoking and infection, although three of these looked at people with a genetic propensity to smoke rather than at smokers themselves. 

The studies used a range of methodologies. Very few of them set out to look at the effect of smoking specifically, but epidemiologists tend to ask people if they smoke as a matter of course and so the association kept popping up. Some of the studies looked at specific outbreaks of Covid-19, such as on a French aircraft carrier. Several of them looked at healthcare workers, such as this one from Germany and this one from Chile. Others looked at groups of hospital patients, such as psychiatric patients in New York or HIV patients in South Africa. A large number of them used seroprevalence surveys to see who had antibodies and, therefore, who had been infected in the past (prior to the vaccines).