Study cancelled due to change in feasibility.

The main purpose of this study is to understand:

• the symptoms of COVID-19 or influenza
• health-related outcomes of people with COVID-19 or influenza
• the effects of vaccines in people with COVID-19 or influenza.

This study will take in participants who are:

• 18 years or older
• reported to have symptoms with lab tests that have confirmed illness. The lab tests can be tested at any of Walgreens pharmacy COVID-19 or influenza test sites.

The study will collect vaccine history information from participants who are ready to take part in the study. Participant will be emailed a form with questions about their health related to COVID-19 or influenza during twelve follow-ups over a 6-month period.

This is a prospective non-interventional longitudinal cohort survey study. Repeated measures on PROs: symptoms (prevalence, frequency, duration, and severity), EQ-5D-5L, WPAI and PROMIS-Fatigue short form 8a over 6 months will be collected and evaluated.

COVID-19 Cohort: Participants 18 years or older with laboratory-confirmed COVID-19 illness and at least one patient-reported symptom.

Influenza Cohort: Participants 18 years or older with laboratory-confirmed influenza illness and at least one patient-reported symptom.

All study objectives and outcomes will be assessed separately for the two study cohorts.

Inclusion Criteria:

• Age 18 or older
• Self-reported at least one symptom in the screening questionnaire
• Positive result reported from the laboratory
• Evidence of a personally signed and dated informed consent document indicating that the patient (or a legally acceptable representative) has been informed of all pertinent aspects of the study
• Able to complete the questionnaires by themselves in English

Exclusion Criteria:

• Positive result for both COVID-19 and influenza (coinfection)
• COVID-19 test is done with non-RT-PCR methods such as a rapid antigen test or antibody test

Participants 18 years or older who are self-reported symptomatic, with laboratory-confirmed illness when tested at any of Walgreens pharmacy COVID-19 or influenza test sites, and consent to participate in the study.

Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical\_trials/trial\_data\_and\_results/data\_requests.