COVID-19NCT04331509
COVID-19 Symptom Tracker
An observational study of COVID-19, run by King's College London at 2 sites in 2 countries.
Trial summary
The viral Covid-19 outbreak is now considered a pandemic according to the World Health Organisation (WHO). A free monitoring app 'COVID-19 Symptom Tracker' has been developed to record and monitor the symptoms of the COVID-19 coronavirus infection; tracking in real time how the disease progresses. Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- COVID-19
- How many people
- 10,000,000 participants
- Where
- 2 sitesin 2 countries
- Study dates
- 23 Mar 2020to 23 Mar 2026
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Study population: Anyone who is able to download the app or use the web-based equivalent tool to self-report their symptoms.
Who may be able to join
- Adults of 18 years and above, both in the UK and internationally where the app has been approved for download from the Apple App store and Google Play. The web-based equivalent to the app will also be made available via a link for those unable to download.
Who cannot join
- Anyone below the age of 18; anyone unable to provide informed consent.
Trial locations and contacts
2 sites in 2 countries.
2 sites in 2 countries
United States1 site
Massachusetts General Hospital
Boston, Massachusetts, 02114
About this study
The viral Covid-19 outbreak is now considered a pandemic according to the World Health Organisation (WHO). A free monitoring app 'COVID-19 Symptom Tracker' has been developed to record and monitor the symptoms of the COVID-19 coronavirus infection; tracking in real time how the disease progresses. The app also records how measures aimed at controlling the pandemic including self-isolation and distancing are affecting the mental health and well-being of participants. The data from the study will reveal important information about the symptoms and progress of COVID-19 infection in different people, and why some go on to develop more severe or fatal disease while others have only mild symptoms do not.
Read the detailed description
A free monitoring app 'COVID-19 Symptom Tracker' has been developed by health technology company Zoe Global Limited in collaboration with scientists at King's College London, Harvard Medical School, Massachusetts General Hospital and Stanford University. A web-based equivalent is being developed for those unable to download this app. This new app records and monitors the symptoms of COVID-19 coronavirus infection; tracking in real time how the disease progresses. The app also records how measures aimed at controlling the pandemic including self-isolation and distancing affect the mental health and well-being of participants. The app also allows self-reporting where no symptoms are experienced such that it records any users that feel healthy and normal.
The app, has been launched in both the UK and the US. Researchers in other countries are encouraged to obtain the required approvals from Apple and Google to make the app available in their territories.
The data from the study will reveal important information about the symptoms and progress of COVID-19 infection in different people, and why some go on to develop more severe or fatal disease while others have only mild symptoms do not.
It is also hoped that the data generated from this study will help the urgent clinical need to distinguish mild coronavirus symptoms from seasonal coughs and colds, which may be leading people to unnecessarily self-isolate when they aren't infected or inadvertently go out and spread the disease when they are.
Users download the free app COVID-19 Symptom Tracker and record information about their health on a daily basis, including temperature, tiredness and symptoms such as coughing, breathing problems or headaches.
The app is available internationally to the general population and will also be used in two large epidemiological cohorts: The TwinsUK cohort (n=15,000) and Nurses Health Study (n=280,000).
The app will allow scientists to study the spread and development of symptoms across whole populations, both in the UK and abroad, as well as detailed genetic and other studies, particularly with the twins cohort
Any data gathered from the app and study will be used strictly for public health or academic research and will not be used commercially or sold.
- Conditions
- COVID-19
- Being tested
- No Intervention
- Keywords
- COVID-19, Coronovirus, Symptom tracker, Virus, Pandemic
- Medical subject headings
- COVID-19, Virus Diseases
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
No InterventionOther
No Intervention
| Study group | Role | What they receive |
|---|---|---|
| Symptom tracker users | No Intervention Receives: Other: No Intervention |
What is being measured
The primary outcome is the main question the study is designed to answer.
Physical health symptoms
Self reported as physically healthy (tick box)
Measured: 1 day
Lack of physical health symptoms
Self reported as physically not feeling healthy (tick box)
Measured: 1 day
Secondary outcomes (1)
Fever
Self reported remperature (Degrees Celsius)
Measured: 1 day
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted2 Apr 2020
- Study start23 Mar 2020
- Primary completion23 Mar 2026 (estimated)
- Study completion23 Mar 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (2)Papers the sponsor has linked to this study.
- Other trials for COVID-19Studies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 10,000,000 participants (estimated)
Sponsor and investigators
- Lead sponsor
- King's College London
- Sponsor type
- University, hospital or other
- Collaborators
- Zoe Global Limited, Massachusetts General Hospital, Harvard School of Public Health (HSPH), Stanford University
- Responsible party
- Sponsor
- Investigators
- Tim D Spector, Principal investigator, King's College London
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04331509
- Sponsor's protocol ID
- COVID-19 Symptom tracker
- Status last verified
- Mar 2025
- First submitted
- 31 Mar 2020
- Last updated
- 13 Mar 2025
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Access to the COVID-19 Symptom Tracker data will be given to members of the clinical or scientific community as outlined below in accordance with the following privacy policies: https://covid.joinzoe.com/privacy-notice https://storage.googleapis.com/covid-symptom-tracker-public/privacy-policy-us.pdf
Publications
Lo CH, Nguyen LH, Drew DA, Warner ET, Joshi AD, Graham MS, Anyane-Yeboa A, Shebl FM, Astley CM, Figueiredo JC, Guo CG, Ma W, Mehta RS, Kwon S, Song M, Davies R, Capdevila J, Sudre CH, Wolf J, Cozier YC, Rosenberg L, Wilkens LR, Haiman CA, Marchand LL, Palmer JR, Spector TD, Ourselin S, Steves CJ, Chan AT; COPE Consortium. Race, ethnicity, community-level socioeconomic factors, and risk of COVID-19 in the United States and the United Kingdom. EClinicalMedicine. 2021 Aug;38:101029. doi: 10.1016/j.eclinm.2021.101029. Epub 2021 Jul 17.
PubMed 34308322Nguyen LH, Drew DA, Graham MS, Joshi AD, Guo CG, Ma W, Mehta RS, Warner ET, Sikavi DR, Lo CH, Kwon S, Song M, Mucci LA, Stampfer MJ, Willett WC, Eliassen AH, Hart JE, Chavarro JE, Rich-Edwards JW, Davies R, Capdevila J, Lee KA, Lochlainn MN, Varsavsky T, Sudre CH, Cardoso MJ, Wolf J, Spector TD, Ourselin S, Steves CJ, Chan AT; COronavirus Pandemic Epidemiology Consortium. Risk of COVID-19 among front-line health-care workers and the general community: a prospective cohort study. Lancet Public Health. 2020 Sep;5(9):e475-e483. doi: 10.1016/S2468-2667(20)30164-X. Epub 2020 Jul 31.
PubMed 32745512
Study at a glance
From the registry record, last updated by the sponsor on 13 Mar 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- COVID-19 Symptom Tracker
- ClinicalTrials.gov ID
- NCT04331509
- Acronym / sponsor ID
- COVID-19 Symptom tracker
- Conditions
- COVID-19
- Keywords
- COVID-19, Coronovirus, Symptom tracker, Virus, Pandemic
- Study type
- Observational
- Recruitment status
- Active, not recruiting
- Enrolment
- 10,000,000 participants (estimated)
- Lead sponsor
- King's College LondonUniversity, hospital or other
- Collaborators
- Zoe Global Limited, Massachusetts General Hospital, Harvard School of Public Health (HSPH), Stanford University
- Study start
- 23 Mar 2020 (actual)
- Primary completion
- 23 Mar 2026 (estimated)
- Study completion
- 23 Mar 2026 (estimated)
- First posted
- 2 Apr 2020 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The viral Covid-19 outbreak is now considered a pandemic according to the World Health Organisation (WHO). A free monitoring app 'COVID-19 Symptom Tracker' has been developed to record and monitor the symptoms of the COVID-19 coronavirus infection; tracking in real time how the disease progresses. The app also records how measures aimed at controlling the pandemic including self-isolation and distancing are affecting the mental health and well-being of participants. The data from the study will reveal important information about the symptoms and progress of COVID-19 infection in different people, and why some go on to develop more severe or fatal disease while others have only mild symptoms do not.
Detailed description
A free monitoring app 'COVID-19 Symptom Tracker' has been developed by health technology company Zoe Global Limited in collaboration with scientists at King's College London, Harvard Medical School, Massachusetts General Hospital and Stanford University. A web-based equivalent is being developed for those unable to download this app. This new app records and monitors the symptoms of COVID-19 coronavirus infection; tracking in real time how the disease progresses. The app also records how measures aimed at controlling the pandemic including self-isolation and distancing affect the mental health and well-being of participants. The app also allows self-reporting where no symptoms are experienced such that it records any users that feel healthy and normal.
The app, has been launched in both the UK and the US. Researchers in other countries are encouraged to obtain the required approvals from Apple and Google to make the app available in their territories.
The data from the study will reveal important information about the symptoms and progress of COVID-19 infection in different people, and why some go on to develop more severe or fatal disease while others have only mild symptoms do not.
It is also hoped that the data generated from this study will help the urgent clinical need to distinguish mild coronavirus symptoms from seasonal coughs and colds, which may be leading people to unnecessarily self-isolate when they aren't infected or inadvertently go out and spread the disease when they are.
Users download the free app COVID-19 Symptom Tracker and record information about their health on a daily basis, including temperature, tiredness and symptoms such as coughing, breathing problems or headaches.
The app is available internationally to the general population and will also be used in two large epidemiological cohorts: The TwinsUK cohort (n=15,000) and Nurses Health Study (n=280,000).
The app will allow scientists to study the spread and development of symptoms across whole populations, both in the UK and abroad, as well as detailed genetic and other studies, particularly with the twins cohort
Any data gathered from the app and study will be used strictly for public health or academic research and will not be used commercially or sold.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Symptom tracker users | – | Other: No InterventionNo Intervention |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
- Study population
- Anyone who is able to download the app or use the web-based equivalent tool to self-report their symptoms.
Key inclusion criteria (1 listed)
- Adults of 18 years and above, both in the UK and internationally where the app has been approved for download from the Apple App store and Google Play. The web-based equivalent to the app will also be made available via a link for those unable to download.
Key exclusion criteria (1 listed)
- Anyone below the age of 18; anyone unable to provide informed consent.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| No InterventionNo Intervention | Other | Symptom tracker users |
Primary outcome
Physical health symptoms
Time frame: 1 day
Self reported as physically healthy (tick box)
Lack of physical health symptoms
Time frame: 1 day
Self reported as physically not feeling healthy (tick box)
1 secondary outcome
Fever
Time frame: 1 day
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 13 Mar 2025.
- Derived from this study: PubMed 34308322Lo CH, Nguyen LH, Drew DA, Warner ET, Joshi AD, Graham MS, Anyane-Yeboa A, Shebl FM, Astley CM, Figueiredo JC, Guo CG, Ma W, Mehta RS, Kwon S, Song M, Davies R, Capdevila J, Sudre CH, Wolf J, Cozier YC, Rosenberg L, Wilkens LR, Haiman CA, Marchand LL, Palmer JR, Spector TD, Ourselin S, Steves CJ, Chan AT; COPE Consortium. Race, ethnicity, community-level socioeconomic factors, and risk of COVID-19 in the United States and the United Kingdom. EClinicalMedicine. 2021 Aug;38:101029. doi: 10.1016/j.eclinm.2021.101029. Epub 2021 Jul 17.
- Derived from this study: PubMed 32745512Nguyen LH, Drew DA, Graham MS, Joshi AD, Guo CG, Ma W, Mehta RS, Warner ET, Sikavi DR, Lo CH, Kwon S, Song M, Mucci LA, Stampfer MJ, Willett WC, Eliassen AH, Hart JE, Chavarro JE, Rich-Edwards JW, Davies R, Capdevila J, Lee KA, Lochlainn MN, Varsavsky T, Sudre CH, Cardoso MJ, Wolf J, Spector TD, Ourselin S, Steves CJ, Chan AT; COronavirus Pandemic Epidemiology Consortium. Risk of COVID-19 among front-line health-care workers and the general community: a prospective cohort study. Lancet Public Health. 2020 Sep;5(9):e475-e483. doi: 10.1016/S2468-2667(20)30164-X. Epub 2020 Jul 31.
- Individual participant dataSharing planned: Yes. Access to the COVID-19 Symptom Tracker data will be given to members of the clinical or scientific community as outlined below in accordance with the following privacy policies: https://covid.joinzoe.com/privacy-notice https://storage.googleapis.com/covid-symptom-tracker-public/privacy-policy-us.pdf
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Tim D Spector principal investigator
King's College London
2 sites in 2 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of COVID-19, run by King's College London at 2 sites in 2 countries.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 1 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: under way, not looking for participants, as of the sponsor's last update on 13 Mar 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 2 sites in United States, United Kingdom. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Physical health symptoms (time frame: 1 day). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT04331509, which also lists 2 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 13 Mar 2025.