In July last year, a paper suggested something quite counterintuitive: that smokers might be less at risk of contracting COVID-19, and less likely to suffer severe outcomes from the disease if they contracted it.
"Current smokers were 23% less likely to be diagnosed with COVID-19 compared to non-smokers," the study published in the European Respiratory Journal read. "Of all COVID-19 patients, 34.8% were hospitalized and 13.0% experienced an adverse outcome. Male gender, older age, having one or more comorbidities, and chronic renal disease, diabetes, obesity, COPD, immunosuppression and hypertension were associated with hospitalization and adverse outcome. Current smoking was not associated with adverse outcome."
The early view paper was picked up by several big news outlets, but has now been retracted by the journal after the editors were informed of links between two of the study's authors and the tobacco industry.
When the paper was published, the authors declared that they had no competing interests. However, in the retraction notice, the European Respiratory Journal noted that they had failed to disclose that "one of the authors (José M. Mier) at the time had a current and ongoing role in providing consultancy to the tobacco industry on tobacco harm reduction; and another (Konstantinos Poulas) at the time was a principal investigator for the Greek NGO NOSMOKE," they wrote. "A science and innovation hub that has received funding from the Foundation for a Smoke Free World (an organisation funded by the tobacco industry)."
The journal's editors went on to state that there weren't questions of scientific misconduct, but felt they should withdraw the paper given the sensitive subject matter presented and the nature of the undisclosed relationship involved.
The findings of the paper are at odds with further studies, which have found that smokers may experience a wider range of COVID-19 symptoms and be more likely to attend hospitals than non-smokers. In a review of the topic for BMJ Evidence-Based Medicine in August 2020, the authors concluded that there wasn't enough evidence to infer a protective effect of smoking, adding:
"Claims that smoking is protective in COVID-19 can be detrimental to public health and should be viewed with extreme caution by both the general population as well as clinicians. Even if smoking did offer a protective effect in COVID-19, this is unlikely to outweigh the numerous proven adverse health effects of smoking."
The corresponding author of the now-retracted paper – Konstantinos Farsalinos – told Retraction Watch that "the discussed conflicts were irrelevant to the study’s main aims and objectives", and that that he had offered to release the full dataset and statistical script so that the results could be independently verified.
"I disagree with the retraction and I consider it unfair and unsubstantiated," he added. "I fully support the accuracy of all analyses and content, and we will submit the same manuscript to another journal."