Researchers help develop heat map to monitor movement during COVID-19 pandemic

Researchers from the University’s Institute of Population Health Sciences and Department of Electrical Engineering and Electronics, working with colleagues at The University of Manchester and Evergreen Life Ltd, have developed a live map of COVID-19 symptoms from an app that connects patients to their GP records and asks them questions about their health.

The Evergreen Life app ( is used by patients to book GP appointments, order repeat prescriptions, access their NHS GP records and record personal wellbeing information.

In response to COVID-19 the company started asking its app users about symptoms that might give early warning of how the pandemic is affecting communities. They pushed out questions via the app and asked our research teams to help them analyse the data and design further questions.

Users of the app from across the UK are being asked to report if they are self-isolating, have a fever or a dry cough. The anonymised data are used to create a national picture of those reporting symptoms. People are also asked to report when they recover.

App users are sent personalised information on national guidance, to help support their wellbeing. The platform is also being offered to give the advice from the NHS for users within the 1.5m “shielded” people identified to be at highest risk from the virus.

Leading universities, including Liverpool and Manchester, are helping the Evergreen team analyse the anonymised data.

Data from 25,548 responses of app users shows that by March 27, 10.4% of respondents had reported having the symptoms consistent with COVID-19, up from 8.1% in the initial survey on March 22, before lockdown was announced.

Before lockdown, 53% with symptoms were staying at home and after lockdown 89% with symptoms reported they were staying at home – showing that the majority of those with symptoms were acting on Government advice to self-isolate.

Professor Iain Buchan, Executive Dean of the Institute of Population Health and Chair in Public Health and Clinical Informatics, University of Liverpool, is one of the researchers analysing the data.

Professor Buchan is also working in the Merseyside Resilience Forum on his local community’s COVID-19 response while leading epidemiological research in the Liverpool Malawi COVID-19 initiative (

Professor Buchan, said: “As part of the University’s response to COVID-19 we have public health researchers and data scientists putting the clues together from different data sources on how the virus and the public health responses to it are affecting people.

“The Evergreen app enables us quickly to ask questions of large numbers of people about their symptoms, giving an earlier and more complete picture than NHS data alone can show. Using anonymised data linked, with patients’ consent, to their GP records, we may see how people with different conditions and medications in different regions get on over time.

“This is also an important way to explore how the control measures are affecting health and wellbeing. Right now, the more people who report their symptoms and experiences in this way, the more information local services have to best prepare themselves.”

Professor Simon Maskell, from the Department of Electrical Engineering and Electronics, said: “To be confident in making effective decisions in the midst of this pandemic, we need to reduce the uncertainty associated with our predictions.

“The best way to achieve that will be to empower the epidemiological models already being used with a combination of information from each of many disparate data sources, all of which provide different perspectives on what’s happening. Evergreen’s data is already making a key contribution by giving us both early sight of likely trends in future hospital admissions and indications of where COVID-19 is most likely to spread most quickly in the future.

“The potential to ask pertinent questions of the individuals and to capitalise on data pertinent to the individuals’ medical history, in a framework that has been built to incorporate informed consent and anonymity, means that Evergreen’s data has significant potential to do even more to help win this battle with COVID-19. ”

Evergreen Life CEO Stephen Critchlow, said: “We’ve asked our 750,000 users to help build a heat map of those with symptoms of COVID-19 to help the NHS and researchers better understand how the virus is moving and spreading around the UK. We’ve already heard from over 25,000 people and the questionnaire has been completed over 40,000 times.

“We have compared the situation before and after lockdown. It shows that while many more people are now staying at home, the number of people reporting symptoms has risen from 8.1% to 10.4%.”

The Heat Map is available here