A Study to Look at the Health Outcomes of Patients With COVID-19 and Influenza

March 30, 2026 updated by: Pfizer

Patient-Reported Outcomes Associated With COVID-19 and Influenza: A Prospective Survey Study on Outpatient Symptomatic Adults With Test-Confirmed Illness in the United States

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 (influenza only included in updated study analyses)
  • the potential effects of COVID-19 vaccines in people with COVID-19

This study will enroll participants who are:

  • 18 years or older
  • reported to have symptoms with tests that have confirmed illness. The tests can be taken at any of CVS 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 multiple follow-ups over a 6-month period.

Study Overview

Status

Active, not recruiting

Conditions

Intervention / Treatment

Detailed Description

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.

Study Type

Observational

Enrollment (Estimated)

999

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • New York
      • New York, New York, United States, 10001
        • Pfizer

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

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.

Description

Inclusion Criteria:

  • Age 18 or older
  • Self-reported at least one symptom in the CVS Health pre-test screening questionnaire
  • Positive result reported from diagnostic test for COVID-19 (or influenza in updated analysis)
  • Evidence of a signed and dated informed consent through electronic consent process indicating that the participant has been informed of all pertinent aspects of the study
  • Able to complete the questionnaires by themselves in English or Spanish

Exclusion Criteria:

- No symptoms reported in the study screening questionnaire

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Observational Models: Case-Only
  • Time Perspectives: Prospective

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
COVID-19 Positive
Test-confirmed COVID-19 illness and at least one patient-reported symptom
Biological: COVID-19 Vaccine
Receipt of Pfizer BioNTech COVID-19 vaccine
Influenza Positive
Test-confirmed influenza illness and at least one patient-reported symptom

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in Health Related Quality of Life (HRQoL) using EQ-5D-5L
Time Frame: 6 months
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.
6 months
EQ-5D-5L Utility Index (UI) scores
Time Frame: 6 months
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.
6 months
Visual Analog Scale (VAS) scores
Time Frame: 6 months
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.
6 months
WPAI scores
Time Frame: 6 months
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.
6 months

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Fatigue before COVID-19
Time Frame: 6 months
To assess fatigue (using PROMIS questionnaire Fatigue short-form 8a) before COVID-19 and over a six-month follow-up.
6 months
Fatigue after COVID-19
Time Frame: 6 months
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.
6 months
Prevalence and duration of SARS-CoV-2 symptoms
Time Frame: 6 months
To characterize prevalence and duration of SARS-CoV-2 symptoms before COVID-19 and up to 6 months (acute phase and Long COVID).
6 months
Prevalence, Severity, and duration of influenza symptoms aggregated as index score area under the curve
Time Frame: 6 Months
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.
6 Months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Pfizer

Collaborators

CVS Caremark

Investigators

  • Study Director: Pfizer CT.gov Call Center, Pfizer

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

January 31, 2022

Primary Completion (Estimated)

January 31, 2027

Study Completion (Estimated)

January 31, 2027

Study Registration Dates

First Submitted

December 15, 2021

First Submitted That Met QC Criteria

December 15, 2021

First Posted (Actual)

December 16, 2021

Study Record Updates

Last Update Posted (Actual)

March 31, 2026

Last Update Submitted That Met QC Criteria

March 30, 2026

Last Verified

January 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • C4591034
  • NCT05160636 (Registry Identifier: ClinicalTrials.gov)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

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.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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