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Citizen science in the time of COVID-19
  1. Linda J Birkin1,
  2. Eleftheria Vasileiou2,
  3. Helen Ruth Stagg3
  1. 1 Independent researcher, Nottingham, UK
  2. 2 Centre for Medical Informatics, Usher Institute, University of Edinburgh, Edinburgh, UK
  3. 3 Centre for Population Health Sciences, Usher Institute, University of Edinburgh, Edinburgh, UK
  1. Correspondence to Dr Helen Ruth Stagg, Centre for Global Health Research, Usher Institute, MacKenzie House, University of Edinburgh, Edinburgh EH8 9AG, UK; helen.stagg{at}

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The COVID-19 pandemic has been a masterclass in the need for accurate, population-wide, frequently updated and rapidly analysed digital data sources in global health.

This issue of Thorax presents two studies using data from the smartphone Zoe COVID Symptom Study app, which has been collecting voluntarily self-reported information from consenting participants ≥18 years on COVID in the UK since its launch in March 2020. As of 16 December 2020, 4 481 148 individuals had registered to use the app across the UK, USA and Sweden.1 While there are other citizen science studies running in the UK to track COVID symptoms (eg, FluSurvey/Influenzanet and TrackTogether), the Zoe COVID app is by far the most extensive of these in coverage and participation numbers, and has contributed, for example, to identification of anosmia as a key symptom of COVID-19 in general (in May 2020),2 and delirium as a key symptom in older people (October 2020).3

In this issue, Hopkinson et al sought to examine the impact of current smoking on the development of COVID-19, using data from March to April 2020.4 Among individuals who did not think they had previously had COVID-19, self-declared current smokers reported slightly increased odds for presenting the classic triad (cough, fever and breathlessness) of symptoms than non-smokers (OR: 1.14 (95% CI: 1.10 to 1.18)), in results adjusted for age, sex and body mass index. This association did not hold when analyses were constricted to individuals tested for SARS-CoV-2 (OR: 0.73 (95% CI: 0.65 to 0.81)), including after adjustment for potential confounding due to being a healthcare worker …

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  • LJB and EV are joint first authors.

  • Contributors All authors conceived of and designed the work, drafted it and critically revised it for content, approval the final version to be published and agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

  • Funding HRS is funded by the Medical Research Council, UK [MR/R008345/1].

  • Competing interests HRS is an advisor to the Scottish Parliament’s COVID-19 committee and is an author on a paper using the Zoe app data.

  • Provenance and peer review Commissioned; externally peer reviewed.

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