RT Journal Article SR Electronic T1 Current smoking and COVID-19 risk: results from a population symptom app in over 2.4 million people JF Thorax JO Thorax FD BMJ Publishing Group Ltd and British Thoracic Society SP 714 OP 722 DO 10.1136/thoraxjnl-2020-216422 VO 76 IS 7 A1 Hopkinson, Nicholas S A1 Rossi, Niccolo A1 El-Sayed_Moustafa, Julia A1 Laverty, Anthony A A1 Quint, Jennifer K A1 Freidin, Maxim A1 Visconti, Alessia A1 Murray, Ben A1 Modat, Marc A1 Ourselin, Sebastien A1 Small, Kerrin A1 Davies, Richard A1 Wolf, Jonathan A1 Spector, Tim D A1 Steves, Claire J A1 Falchi, Mario YR 2021 UL http://thorax.bmj.com/content/76/7/714.abstract AB 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.Data may be obtained from a third party and are not publicly available. Anonymised research data will be shared with third parties via the centre for Health Data Research UK (HDRUK.ac.uk). Data updates can be found on https://COVID.joinzoe.com.