Misleading: Several studies show smokers are less likely to catch COVID-19.

Context

An article published in the e-magazine Spiked claims that dozens of studies brought out in the last two and half years prove that "smokers are less likely to get COVID-19." In the article, which has been shared by several Facebook users, author Christopher Snowdon claims that this "truth has been buried", and alleges a major "coverup" by "Big Tech fact-checkers." He contends that there had been a concerted effort by public health experts and the World Health Organization(WHO) to misrepresent the evidence on the reduced probability of smokers getting COVID-19. However, while some initial studies did suggest such a finding, subsequent analysis has identified problems with those studies. The latest evidence indicates that smokers are at greater risk of poor outcomes from the virus. 

In Fact

The article includes links to Snowdon's blog, where he has compiled a list of studies (including those published by reputed medical journals such as Lancet and Nature), and claims that an overwhelming “87 percent” of the studies acknowledge that smokers are typically less likely to catch the virus and be hospitalized.

On reviewing the exhaustive list of studies that Snowdon refers to, Logically found that several of them are pre-prints rather than peer-reviewed published papers. The author himself says that he has not done a "systematic review" of all the studies that have been listed.

In an article published in The Lancet on August 16, 2022, Professor John Griggs, a respiratory and environmental medicine specialist, acknowledged that there were studies in the early stages of the pandemic that appeared to provide evidence that smoking might protect against COVID-19. However, he also noted that during those early stages of the pandemic, "scientific journals rightly responded to the SARS-CoV-2 pandemic by more rapidly publishing their COVID-19 research”. While this was largely beneficial, he argues that "in some cases, the significant limitations of this rapidly disseminated knowledge (with lowering the standard of COVID-19 research among other measures) were not sufficiently made apparent." Citing pre-existing research, he observed that an association between smoking and reduced risk of COVID-19 would be "bizarre," as smokers "are five times more likely to develop laboratory-confirmed influenza, and four times more likely to develop the invasive pneumococcal disease than non-smokers." He asserted that exposure to cigarette smoke increases the risk of tuberculosis, Legionnaires disease, Helicobacter pylori infection among various other diseases and infection. 

Prof. Griggs also cited a more detailed article published in The Lancet, which examined epidemiological studies of tobacco use and COVID-19, and found that the studies have produced conflicting results, meaning further research is needed before one can claim that smoking affects susceptibility to the virus. The article nonetheless concludes that "the evidence indicates that smokers are at greater risk of poor outcomes from COVID-19, including hospital admission and progression to severe disease than are non-smokers."

In his article, Snowdon argued that search results for COVID-19 and tobacco/smoking lead to WHO briefs and articles in publications such as the British Medical Journal (BMJ). He claims that these studies merely state that smokers are at greater risk without addressing the actual findings of the studies that suggest smokers had a reduced risk of contracting COVID-19. 

However, in the article published in the BMJ, the authors explain that they have identified several biases and knowledge gaps in the existing literature on the protective effects of smoking. The authors note that the claim about protective effects must be viewed with caution and warrants an accurate assessment of the risk.

Further, in a recent update, the Centers for Disease Control and Prevention (CDC) said that smoking is one of the high-risk underlying conditions of COVID-19. It concluded that the meta-analysis demonstrated smoking would lead to one of the most severe outcomes in the case of COVID-19. The WHO, in an updated 2020 review, which excluded the non-peer-reviewed reports and pre-prints, found that smoking is associated with increased severity of disease and death in hospitalized COVID-19 patients. However, it could not quantify the risk to smokers of infection by SARS-CoV-2 or hospitalization for COVID-19. The brief said that more population studies are needed to address these questions.

Snowdon also claimed in the article that WHO has been spreading misinformation about COVID-19 infection, and articles that appeared on Google searches were obfuscating. However, the WHO article and other studies he refers to only say that research papers on the protective effects of smoking suffer from poor data quality and did not follow adequate peer review. 

Logically also contacted Dr. Satyanarayana Mysore, head of the pulmonology department at Manipal Hospitals in Bengaluru, to get more clarity on the matter. Dr Mysore dismissed the claim that smokers are less likely to catch COVID-19, and said that there are major limitations in the studies associating smoking with with reduced risk of getting COVID-19. He noted that WHO has listed smoking and chronic obstructive pulmonary disease (COPD) as major risk factors for COVID-19. He added that smoking does not protect anyone from COVID-19 and has the potential to harm.

The Verdict

While some reports suggesting the protective effects of smoking against COVID-19 were published during the pandemic's beginning, these studies were later found to be riddled with various problems. These studies were non-peer-reviewed, and had several biases and knowledge gaps. Latest literature suggests growing evidence of risks associated with COVID-19 among smokers, and that more exhaustive research is needed on the subject. Therefore, we have marked the claim as misleading.

The COVID-19 pandemic has given rise to a lot of potentially dangerous misinformation. For reliable advice on COVID-19, including symptoms, prevention, and available treatment, please refer to the World Health Organization or your national healthcare authority.