An observational study in COVID-19, Coronavirus Disease 2019 and Influenza, sponsored by Pfizer. Active, not recruiting at 1 site in United States. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-03-31.
Sponsored by Pfizer · Observational
The main purpose of this study is to understand:
This study will enroll participants who are:
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 multiple follow-ups over a 6-month period.
This is a prospective non-interventional longitudinal cohort survey study. Repeated measures on PROs including: symptoms (prevalence, frequency, duration, and severity), EQ-5D-5L, and WPAI over 6 months will be collected and evaluated.
COVID-19 Cohort: Participants 18 years or older with test-confirmed COVID-19 illness and at least one patient-reported symptom.
Influenza Cohort: Participants 18 years or older with test-confirmed influenza illness and at least one patient-reported symptom.
All study objectives and outcomes will be assessed separately for the two study cohorts. Influenza cohort is only included in updated study analyses.
7,640 studies on the registry are indexed under COVID-19; 488 are open to participants now.
This study's planned enrollment of 999 is above the median of 261 across 3,136 observational studies indexed under COVID-19.
Browse COVID-19 studies →Pfizer is the lead sponsor of 3,244 studies on the registry; 139 are open to participants now.
Of its 582 completed or terminated interventional studies of FDA-regulated products, 381 (65%) have results posted.
Counted across the registry records on this site, refreshed daily.
Participants are 18 years or older who are self-reported symptomatic, who tested positive with RT-PCR at any of the approximately 5,000 CVSH COVID-test sites and consented to participate in the PRO study.
Updated study analysis included participants 18 years or older who are self-reported symptomatic, with test-confirmed illness when tested at any of CVS pharmacy COVID-19 or influenza test sites, and consent to participate in the study.
Exclusion Criteria:
- No symptoms reported in the study screening questionnaire
Test-confirmed COVID-19 illness and at least one patient-reported symptom
Biological: COVID-19 Vaccine
Test-confirmed influenza illness and at least one patient-reported symptom
Receipt of Pfizer BioNTech COVID-19 vaccine
Change in Health Related Quality of Life (HRQoL) using EQ-5D-5L
To assess the change in HRQoL using EQ-5D-5L before COVID-19 or influenza and over a 6-month period following the test-confirmed COVID-19 or influenza.
Time frame: 6 months
EQ-5D-5L Utility Index (UI) scores
To estimate the EQ-5D-5L UI scores and their change across six time points in a span of six months following the test-confirmed COVID-19 or influenza.
Time frame: 6 months
Visual Analog Scale (VAS) scores
To estimate the VAS scores and their change across six time points in a span of six months following the test-confirmed COVID-19 or influenza.
Time frame: 6 months
WPAI scores
To estimate the WPAI scores and their change across six time points in a span of six months following the test-confirmed COVID-19 or influenza.
Time frame: 6 months
Prevalence and duration of SARS-CoV-2 symptoms
To characterize prevalence and duration of SARS-CoV-2 symptoms before COVID-19 and up to 6 months (acute phase and Long COVID).
Time frame: 6 months
Prevalence, Severity, and duration of influenza symptoms aggregated as index score area under the curve
To characterize prevalence and duration of influenza symptoms before influenza and up to 6 months (acute phase and Long Flu). Outcome will be aggregated by assigning a point-scale to the symptom severity and calculating the area under the curve of the severity index score.
Time frame: 6 Months
Fatigue before COVID-19
To assess fatigue (using PROMIS questionnaire Fatigue short-form 8a) before COVID-19 and over a six-month follow-up.
Time frame: 6 months
Fatigue after COVID-19
To estimate the PROMIS questionnaire Fatigue short-form 8a score and its change across six time points in a span of six months following the RT-PCR confirmed COVID-19.
Time frame: 6 months
Plan to share: No — 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.
This study is active, not recruiting, as verified in Jan 2026. You cannot join it, but the record below documents what was studied.
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