Patient case (clinical description): The patient is a 38-year-old man with cough and body ache that started 3 days ago.  He had fever and chills at the beginning and has low grade fever at the time of visit. He feels tired and sleepy. His body ache and myalgia get better after using Tylenol. The PCR test for Covid is positive. His vital signs are within normal limits with a body temperature of 37.9 C. There is no lymphadenopathy or white exudates in the pharynx.

Patient's own account: I was feeling really sick the other day, to the point that I showed up at the doctor's office. I was coughing, and my body was hurting for 3 days. I had a fever and chills and felt tired and sleepy. I got better after using Tylenol. They did a PCR Covid test on me, and it was positive! My vitals were normal, and my temperature was 37.9 C. I had no swelling around my neck or white spots on the back of my throat.

Clinical trial: Testing the Accuracy of a Digital Test to Diagnose Covid-19

Eligibility criteria:
Study Inclusion Criteria - app users will be eligible to join the study if they:

          -  Are based in the UK (are using the UK version of the Covid-19 Symptom Study app, and
             have listed a UK postcode)

          -  Are the primary app user (are reporting directly for themselves)

          -  Are at least 18 years of age

          -  Have not tested positive for a Covid-19 test before (but may have been tested)

        Study Exclusion Criteria - participants are ineligible for the study if they:

          -  Do not meet inclusion criteria

          -  Do not provide informed consent to participate

        Participants will be subject to further screening to identify them as eligible for swab
        testing during the course of the study.

        Swab inclusion criteria - participants will be eligible for swab testing if they:

          -  Have reported in the app at least once in the previous 3 days (days -2 to 0), and at
             least two times in the previous 9 days (days -8 to 0). All reports must be healthy
             (i.e. not experiencing any symptoms).

          -  On the previous day (day 1), have reported that they are experiencing at least one
             symptom described in the app. Symptoms in the app are updated when deemed appropriate
             by study investigators using evidence based reports in the scientific and medical
             field.

          -  Have answered the phenotype fields required for the prediction model with
             physiologically plausible values.

        Swab exclusion criteria - participants are ineligible for swab testing if they:

          -  Are asymptomatic

          -  Do not satisfy the inclusion criteria for testing.

        Insufficient testing capacity:

        If insufficient testing capacity is available for the study population as described, then
        recruitment will be prioritised according to:

          -  Firstly, most recent final healthy report before reporting symptoms

          -  Secondly, highest number of healthy reports during the previous 9 days before
             reporting symptoms

          -  Thirdly, randomised selection to stratify between participants of equal priority
             according to the first two rules above.

        Excess testing capacity:

        If excess testing capacity is available beyond the study population as described, then
        inclusion criteria will be expanded in order to adequately sample across under-represented
        population groups.

        Specifically, on day 7 of each validation phase, investigators will assess:

          -  What excess testing capacity is available, if any

          -  Which subgroups are under-represented compared to their proportion in the UK
             population (as best as can be established given that some participants may not have
             completed some phenotype fields):

             (i) Age decade (ii) Sex (iii) Ethnicity (iv) BMI category

        For underrepresented groups, investigators may additionally recruit participants with only
        one report during the previous 3 days (days -2 to 0) and no other report during the
        previous 9 days (days -8 to 0).
No condition on gender to be admitted to the trial.

Subject must be at least 18 Years old.


Eligibility (NLI label): Contradiction