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OpenTrials
Completed

NCT Number: NCT07261085

A Study to Learn How Paxlovid [Nirmatrelvir-ritonavir/PF-07321332] Works in COVID-19 Patients Who Are Elderly or Have Medical Conditions.

The purpose of this study is to learn about the effects of the study medicine called Paxlovid [nirmatrelvir-ritonavir/PF-07321332], for the potential treatment of COVID-19.

This study will use patient health records in Ontario, to find people who were sick with COVID-19 and visited a pharmacist to be treated, anytime from December 1st, 2022, to March 31st, 2024. To be included in our study, the people must be over 18 years of age and be registered in the Ontario health system for at least one year. People were not included in our study if they have been pregnant in the past year or have serious kidney or liver disease.

We will separate the people in the study into two groups: those who received treatment with Paxlovid [nirmatrelvir-ritonavir/PF-07321332] and those who received no treatment. We will monitor their healthcare visits or if they die for any reason, for up to 60 days after the date that they visited their pharmacist. Then we will compare participant experiences when they are taking the study medicine to when they are not. This will help us determine if the study medicine is effective.

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Key information

Conditions

COVID-19 Coronaviridae Infections Coronavirus Infections Infections Lung Diseases Nidovirales Infections Pneumonia Pneumonia, Viral RNA Virus Infections Respiratory Tract Diseases Respiratory Tract Infections Virus Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Observational

Primary location

Pfizer New York

New York, 10001, United States

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion

  • Record of at least 1 nirmatrelvir-ritonavir prescription and at least 1 dispensation issued by the pharmacist (Treated Cohort only) within 5 days of prescription, identified through pharmacy billing codes
  • Record of at least 1 assessment for nirmatrelvir-ritonavir, without a prescription issued by the pharmacist (Untreated Cohort only), OR record of at least 1 prescription for nirmatrelvir-ritonavir without dispensation (Untreated Cohort only), identified through pharmacy billing codes

Exclusion

  • Invalid or incomplete records (e.g., missing age, missing sex, death before index)
  • Record of a positive PCR test for SARS-CoV-2 between 5 and 90 days prior to the index date
  • Had a prescription for antivirals within 3 days prior to or on the index date

Treatment and study plan

nirmatrelvir-ritonavir

Drug

Participants who were assessed with Covid prescribed and subsequently dispensed nirmatrelvir-ritonavir during the selection period

Other names: paxlovid

No treatment

Other

Participants who were assessed with Covid for nirmatrelvir-ritonavir but either were not prescribed the medication or did not have it dispensed during the selection period

Primary outcomes

  1. Time to the first severe composite outcome (all-cause hospital admission, ICU admission, or death) within 30 days of treatment assessment.

    Time frame: Participants selected between 01 Dec, 2022 to 31 March 2024

Secondary outcomes

  1. Time to the first severe composite outcome (all-cause hospital admission, ICU admission, or death) within 60 days of treatment assessment.

    Time frame: Participants selected between 01 Dec, 2022 to 31 March 2024

Sponsors and collaborators

Lead sponsor

Pfizer

Industry

Registry information

Official study title

A REAL-WORLD STUDY ON THE EFFECTIVENESS OF NIRMATRELVIR-RITONAVIR IN REDUCING SEVERE OUTCOMES FROM COVID-19

Important dates

Study start
2025
Primary completion
2026
Study completion
2026
First posted
Dec 3, 2025
Registry last updated
Jun 29, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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