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. 2021 Jul;76(7):714-722.
doi: 10.1136/thoraxjnl-2020-216422. Epub 2021 Jan 5.

Current smoking and COVID-19 risk: results from a population symptom app in over 2.4 million people

Nicholas S Hopkinson  1 , Niccolo Rossi  2 , Julia El-Sayed Moustafa  2 , Anthony A Laverty  3 , Jennifer K Quint  4 , Maxim Freidin  5 , Alessia Visconti  2 , Ben Murray  6 , Marc Modat  6 , Sebastien Ourselin  7 , Kerrin Small  2 , Richard Davies  8 , Jonathan Wolf  8 , Tim D Spector  2 , Claire J Steves #  2 , Mario Falchi #  2
Affiliations

Current smoking and COVID-19 risk: results from a population symptom app in over 2.4 million people

Nicholas S Hopkinson et al. Thorax. 2021 Jul.

Abstract

Background: The association between current tobacco smoking, the risk of developing symptomatic COVID-19 and the severity of illness is an important information gap.

Methods: UK users of the Zoe COVID-19 Symptom Study app provided baseline data including demographics, anthropometrics, smoking status and medical conditions, and were asked to log their condition daily. Participants who reported that they did not feel physically normal were then asked by the app to complete a series of questions, including 14 potential COVID-19 symptoms and about hospital attendance. The main study outcome was the development of 'classic' symptoms of COVID-19 during the pandemic defined as fever, new persistent cough and breathlessness and their association with current smoking. The number of concurrent COVID-19 symptoms was used as a proxy for severity and the pattern of association between symptoms was also compared between smokers and non-smokers.

Results: Between 24 March 2020 and 23 April 2020, data were available on 2 401 982 participants, mean (SD) age 43.6 (15.1) years, 63.3% female, overall smoking prevalence 11.0%. 834 437 (35%) participants reported being unwell and entered one or more symptoms. Current smokers were more likely to report symptoms suggesting a diagnosis of COVID-19; classic symptoms adjusted OR (95% CI) 1.14 (1.10 to 1.18); >5 symptoms 1.29 (1.26 to 1.31); >10 symptoms 1.50 (1.42 to 1.58). The pattern of association between reported symptoms did not vary between smokers and non-smokers.

Interpretation: These data are consistent with people who smoke being at an increased risk of developing symptomatic COVID-19.

Keywords: clinical epidemiology; respiratory infection; tobacco and the lung; viral infection.

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Conflict of interest statement

Competing interests: NSH is Chair of Action on Smoking and Health and Medical Director of The British Lung Foundation. TDS is a consultant to Zoe Global Ltd (Zoe), who developed the app. JW and RD are employees of Zoe Global Ltd.

Comment in

  • Citizen science in the time of COVID-19.
    Birkin LJ, Vasileiou E, Stagg HR. Birkin LJ, et al. Thorax. 2021 Jul;76(7):636-637. doi: 10.1136/thoraxjnl-2020-216673. Epub 2021 Mar 2. Thorax. 2021. PMID: 33653934 No abstract available.

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