Smoking may increase risk for developing symptomatic COVID-19

Current smoking appears to increase individual risk for developing symptomatic COVID-19, according to results published in Thorax.

“Tobacco smoking is a significant risk factor for both viral and bacterial infections of the respiratory system with smokers five times as likely to develop influenza and twice as likely to have pneumonia,” Nicholas S. Hopkinson, PhD, honorary respiratory consultant physician and clinical lead for COPD at Royal Brompton Hospital, London, and medical director at the British Lung Foundation, and colleagues wrote. “It may therefore be an important factor worsening the impact of SARS-CoV-2.”

Researchers conducted a large prospective population cohort study that included data on 2,401,982 participants in the United Kingdom (mean age, 43.6 years; 63.3% women) who used the COVID-19 Symptom Study app (Zoe Global) in March and April 2020. Demographics, anthropometrics, smoking status and medical conditions were obtained. Those who reported not feeling physically normal were prompted by the app to respond to questions about COVID-19 symptoms and hospital attendance.

The primary outcome was development of, what the researchers called, the classic triad ofCOVID-19 symptoms, including fever, new persistent cough and breathlessness, and the association of these symptoms with smoking.

Thirty-five percent of participants reported feeling unwell and reported one or more classic symptoms of COVID-19. Current smokers were more likely to report symptoms that suggested a COVID-19 diagnosis. The researchers reported an adjusted OR of 1.14 for classic COVID-19 symptoms (95% CI, 1.1-1.18), an aOR of 1.29 for more than five symptoms (95% CI, 1.26-1.31) and an aOR of 1.5 for more than 10 symptoms (95% CI, 1.42-1.58).

“The pattern of associations between symptoms reported did not vary between smokers and nonsmokers, suggesting that the findings cannot be explained by preexisting smoking-related symptoms,” the researchers wrote.

The rate of smoking was 7.4% among individuals who tested positive for SARS-CoV-2 vs. 9.3% among those who tested negative. However, smokers who tested positive had a higher symptom burden than nonsmokers (OR for those presenting with > 10 symptoms = 1.42; 95% CI, 1.09-1.83), according to the results. Current smokers who tested positive also had an increased risk for hospital attendance compared with nonsmokers (OR = 2.11; 95% CI, 1.41-3.11).

According to the researchers, these findings demonstrate evidence supporting the incorporation of smoking cessation and other efforts into public health campaigns to address the COVID-19 pandemic.

“Evidence that current smoking appears to increase individual and thus health system burden from COVID-19 is a strong argument for governments to accelerate rather than pause measures to deliver on tobacco control plans,” the researchers wrote. “These should include options such as polluter-pays levies on tobacco transnationals as they will continue, through the pandemic, to be highly profitable as well as enormously damaging to global health.”