PT - JOURNAL ARTICLE AU - Hayley Holt AU - Mohammad Talaei AU - Matthew Greenig AU - Dominik Zenner AU - Jane Symons AU - Clare Relton AU - Katherine S Young AU - Molly R Davies AU - Katherine N Thompson AU - Jed Ashman AU - Sultan Saeed Rajpoot AU - Ahmed Ali Kayyale AU - Sarah El Rifai AU - Philippa J Lloyd AU - David Jolliffe AU - Olivia Timmis AU - Sarah Finer AU - Stamatina Iliodromiti AU - Alec Miners AU - Nicholas S Hopkinson AU - Bodrul Alam AU - Graham Lloyd-Jones AU - Thomas Dietrich AU - Iain Chapple AU - Paul E Pfeffer AU - David McCoy AU - Gwyneth Davies AU - Ronan A Lyons AU - Christopher Griffiths AU - Frank Kee AU - Aziz Sheikh AU - Gerome Breen AU - Seif O Shaheen AU - Adrian R Martineau TI - Risk factors for developing COVID-19: a population-based longitudinal study (COVIDENCE UK) AID - 10.1136/thoraxjnl-2021-217487 DP - 2021 Nov 03 TA - Thorax PG - thoraxjnl-2021-217487 4099 - http://thorax.bmj.com/content/early/2021/11/02/thoraxjnl-2021-217487.short 4100 - http://thorax.bmj.com/content/early/2021/11/02/thoraxjnl-2021-217487.full AB - Background Risk factors for severe COVID-19 include older age, male sex, obesity, black or Asian ethnicity and underlying medical conditions. Whether these factors also influence susceptibility to developing COVID-19 is uncertain.Methods We undertook a prospective, population-based cohort study (COVIDENCE UK) from 1 May 2020 to 5 February 2021. Baseline information on potential risk factors was captured by an online questionnaire. Monthly follow-up questionnaires captured incident COVID-19. We used logistic regression models to estimate multivariable-adjusted ORs (aORs) for associations between potential risk factors and odds of COVID-19.Results We recorded 446 incident cases of COVID-19 in 15 227 participants (2.9%). Increased odds of developing COVID-19 were independently associated with Asian/Asian British versus white ethnicity (aOR 2.28, 95% CI 1.33 to 3.91), household overcrowding (aOR per additional 0.5 people/bedroom 1.26, 1.11 to 1.43), any versus no visits to/from other households in previous week (aOR 1.31, 1.06 to 1.62), number of visits to indoor public places (aOR per extra visit per week 1.05, 1.02 to 1.09), frontline occupation excluding health/social care versus no frontline occupation (aOR 1.49, 1.12 to 1.98) and raised body mass index (BMI) (aOR 1.50 (1.19 to 1.89) for BMI 25.0–30.0 kg/m2 and 1.39 (1.06 to 1.84) for BMI >30.0 kg/m2 versus BMI <25.0 kg/m2). Atopic disease was independently associated with decreased odds (aOR 0.75, 0.59 to 0.97). No independent associations were seen for age, sex, other medical conditions, diet or micronutrient supplement use.Conclusions After rigorous adjustment for factors influencing exposure to SARS-CoV-2, Asian/Asian British ethnicity and raised BMI were associated with increased odds of developing COVID-19, while atopic disease was associated with decreased odds.Trial registration number ClinicalTrials.gov Registry (NCT04330599).Data are available upon reasonable request. Deidentified participant data are available from the corresponding author (a.martineau@qmul.ac.uk) upon reasonable request, subject to the terms of Research Ethics Committee approval.