Swedish COVID-19 symptom data contribute to accelerating research about pandemic
The global COVID-19 pandemic has increased challenges to healthcare, society and research. Monitoring societal spread of SARS-CoV-2 virus infection in order to mitigate the pandemic’s societal effects is an important part of preventive infection control work. At the beginning of the pandemic, high-quality real-time data on the spread of SARS-CoV-2 in Sweden were lacking. To meet this need, already on April 29 2020 researchers at Lund University launched COVID Symptom Study Sweden, a national research initiative for large-scale analysis of symptoms, exposure, and risk factors associated with COVID-19 infection. This initiative started collecting information using a non-commercial smartphone app in which participants self-reported health and symptoms data.
COVID Symptom Study Sweden is run by Lund University and Uppsala University in collaboration with King’s College London and Zoe Global Ltd (Swedish PIs: prof. Tove Fall, Uppsala University, and prof. Maria Gomez and prof. Paul Franks, Lund University). The project aims to map the spread of COVID-19 in Sweden as well as to increase knowledge about the effect of SARS-CoV-2 on human body. The first aim includes investigation of temporal and geographical trends in SARS-CoV-2 spread and investigations of how changes in national strategies affect the spread.
The second aim focuses on increasing understanding which groups are most likely to be affected by COVID-19, how the disease manifests in terms of symptoms, and the relationship between risk factors and (combinations of) symptoms. The researchers also plan to investigate whether risk factors vary in different stages of infection (early vs. late) as well as the effect of vaccination. A new section of the survey focusing on the effects of COVID-19 vaccination on infection, presentation of symptoms, and risk of long-term COVID-19 has recently been added.
COVID Symptom Study Sweden uses a non-commercial app for data collection from volunteer study participants. Anyone 18 years or older living in Sweden can participate in the study. The app was developed by a health science company ZOE Global Ltd and is available from App Store and Google Play free of charge. Study participants are asked to self-report their health in a health declaration that includes, among other variables, risk factors and previous exposure to COVID-19. They are also asked to provide their postal code. Participants then report regularly (daily) in the app how they are feeling, including any symptoms of illness, results from COVID-19 tests (PCR and antibodies) and whether they have been vaccinated against COVID-19. The study is approved by the Swedish Ethical Review Authority (DNR 2020-01803, 2020-04006, 2020-04145, 2020-04451, 2020-07080).
Today, COVID Symptom Study Sweden has over 206,000 participants and accumulated over 12 million data points. Aggregated results are made available daily using the freely available COVID Symptom Study Sweden dashboard (currently only available in Swedish) which includes maps, trends, symptoms, and participants’ demographical statistics. The tab Arkiv (archive) includes calculated COVID-19 prevalence estimate data using the latest prediction model (updated Jan 2021). In addition, the estimated prevalence data is available through an R package covidsymptom built by the team behind the study. With this package, daily estimated prevalence of symptomatic COVID-19 in Sweden overall, in various counties and in smaller regions (2-digit postcodes) can be easily accessed.
Professor Tove Fall, one of the researchers leading the study, says: “Several public entities are incorporating our results in their work on COVID-19. One example is Helsingborg Municipality, it encourages its citizens to participate as they find the timely data we provide very useful.”
Data collected from the Swedish cohort has already been used in a number of scientific publication, see here for the full list. The most recent publication from the study consortium was published in March 2021: Sudre, C.H., Murray, B., Varsavsky, T. et al. Attributes and predictors of long COVID. Nat Med (2021). DOI: 10.1038/s41591-021-01292-y.
Access to the collected data for use in other research projects
While estimates of symptomatic COVID-19 prevalence and basic demographic information about study participants are available through the project results dashboard and an R package, sharing of raw data with external researchers requires a corresponding ethical permit and a data transfer agreement. The researchers behind COVID Symptom Study Sweden welcome applications for data access. Please see this page for more information on how to apply (only available in Swedish).