Risk factors for developing COVID-19: a population-based longitudinal study (COVIDENCE UK)

Holt, H.; Talaei, M.; Greenig, M.; Zenner, D.; Symons, J.; Relton, C.; Young, K. S.; Davies, M. R.; Thompson, K. N.; Ashman, J.; Rajpoot, S. S.; Kayyale, A. A.; El Rifai, S.; Lloyd, P. J.; Jolliffe, D. A.; Finer, S.; Iliodromiti, S.; Miners, A.; Hopkinson, N. S.; Alam, B.; Pfeffer, P. E.; McCoy, D.; Davies, G. A.; Lyons, R. A.; Griffiths, C. J.; Kee, F.; Sheikh, A.; Breen, G.; Shaheen, S. O.; Martineau, A. R.

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 1st May 2020 to 5th February 2021. Baseline information on potential risk factors was captured by online questionnaire. Monthly follow-up questionnaires captured incident COVID-19. We used logistic regression models to estimate multivariable-adjusted odds ratios (aORs) for associations between potential risk factors and risk of COVID-19. Findings: We recorded 446 incident cases of COVID-19 in 15,227 participants. Increased risk of developing COVID-19 was independently associated with Asian/Asian British vs. White ethnicity (aOR 2.31, 95% CI 1.35-3.95), household overcrowding (aOR per additional 0.5 people/bedroom 1.26, 1.11-1.43), any vs. no visits to/from other households in previous week (aOR 1.33, 1.07-1.64), number of visits to indoor public places (aOR per extra visit per week 1.05, 1.01-1.09), frontline occupation outside health/social care vs. no frontline occupation (aOR 1.49, 1.12-1.98), and raised body mass index (BMI) (aOR 1.51 [1.20-1.90] for BMI 25.0-30.0 kg/m2 and 1.38 [1.05-1.82] for BMI >30.0 kg/m2 vs. BMI <25.0 kg/m2). Atopic disease was independently associated with decreased risk (aOR 0.76, 0.59-0.98). No independent associations were seen for age, sex, other medical conditions, diet, or micronutrient supplement use. Interpretation: After rigorous adjustment for factors influencing exposure to SARS-CoV-2, Asian/Asian British ethnicity and raised BMI were associated with increased risk of developing COVID-19, while atopic disease was associated with decreased risk.