Rapid implementation of mobile technology for real-time epidemiology of COVID-19

David A. Drew; Long H. Nguyen; Claire J. Steves; Jonathan Wolf; Tim D. Spector; Andrew T. Chan

Through rapid deployment of this tool, we can gain critical insights into population dynamics of the disease (Fig. 2) . By collecting participant-reported geospatial data, highlighted as a critical need for pandemic epidemiologic research (16), we can rapidly identify populations 5 with highly prevalent symptoms that may emerge as hot spots for outbreaks. A preliminary snapshot of the first 1.6 million users in the UK over the first five days of use confirms the variability in symptoms reported across suspected COVID-19 cases and is useful for generating and testing broader hypotheses. Users are a mean age of 41 with a range from 18 to 90 years, with 75% female users. Simple visualization of initial results (Fig. 3) demonstrates that among 10 those reporting symptoms by March 27, 2020 (n=265,851) the most common symptoms were fatigue and cough, followed by diarrhea, fever, and anosmia. Shortness of breath was relatively rarely reported. Only 0.2% (n=744) of individuals reporting possible COVID-19 symptoms reported receiving a qPCR test for COVID-19. Among individuals who did undergo a test, cough and fatigue alone or in combination commonly led to testing, but was not highly predictive of a 15 positive test. Similarly, no individuals reporting diarrhea in the absence of other symptoms tested positive. Interestingly, more complex presentations with cough and/or fatigue and at least one additional symptom, including less commonly appreciated symptoms such as diarrhea and anosmia, appeared to be better predictors. In particular, anosmia may be a more sensitive symptom as it was more common than fever in individuals who tested positive. In contrast, fever 20 alone was not particularly discriminatory. However, in combination with lesser appreciated symptoms, a greater frequency of positive tests was observed. These findings suggest that individuals with complex symptomatic presentation perhaps should be prioritized for testing.