Can an antiviral cure long COVID? new trial tests paxlovid

NCT ID NCT05595369

Disease control Sponsor: Kanecia Obie Zimmerman Source: ClinicalTrials.gov ↗

First seen Jun 27, 2026 · Last updated Jun 27, 2026

Summary

This study tested the antiviral drug Paxlovid in 963 adults with Long COVID. The goal was to see if clearing leftover virus or calming the immune system could ease symptoms. Participants received either a 25-day or 15-day course of Paxlovid or a placebo. The trial is complete, but detailed results are not yet available.

What this could mean

Our plain-language read of the trial. This is informational only, not medical advice or a prediction.

Active substance: Paxlovid (nirmatrelvir and ritonavir)
What this could lead to: If it works, this could point toward a treatment for Long COVID by targeting lingering virus or immune problems.
What could go wrong: This is a Phase 2 trial, so results are early and may not lead to a proven treatment. The study is completed but specific outcomes are not yet reported, and benefits may be modest or absent.

This is an AI summary of the original study and may miss details. Read our disclaimer.

Study facts

What this study's own registry entry says, in plain language.

Phase

Phase 2

Tests whether the treatment actually works, and watches for side effects, in a larger group.

Participants

963 people

The number who actually took part.

Started

Jul 2023

Finished

Mar 2025

Lead sponsor

Other sponsor

The registry's catch-all category, for sponsors it does not file as a company, a government agency, or a research network.

Who can take part

This study's own entry requirements. Only the study team can say for certain whether you qualify.

Ages

18 years and older

Sex

Anyone

Healthy volunteers

Not accepted

This study is not open to healthy volunteers. The entry requirements below say who it is open to.

Show the full entry requirements

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. ≥ 18 years of age at the time of enrollment 2. Previous suspected, probably or confirmed SARS-CoV-2 infection, as defined by the Pan American Health Organization\* \*Suspected and probable cases will only be allowed if it occurred before May 1, 2021, and will be limited to 10% of the study population. Otherwise, confirmed cases are required. Suspected case of SARS-CoV-2 infection - Three options, A through C: A. A person who meets the clinical OR epidemiological criteria. Clinical criteria: Acute onset of fever AND cough (influenza-like illness) OR Acute onset of ANY THREE OR MORE of the following signs or symptoms: fever, cough, general, weakness/fatigue, headache, myalgia, sore throat, coryza, dyspnea, nausea, diarrhea, anorexia. Epidemiological criteria: Contact of a probable or confirmed case or linked to a COVID-19 cluster; or B. Acute respiratory infection with history of fever or measured fever of ≥ 38°C; and cough; with onset within the last 10 days; and who requires hospitalization); or C. With no clinical signs or symptoms, NOR meeting epidemiologic criteria with a positive professional use or self-test SARS-CoV-2 antigen-Rapid Diagnostic Test. Probable case of SARS-CoV-2 infection: A. A patient who meets clinical criteria above AND is a contact of a probable or confirmed case or is linked to a COVID-19 cluster. Confirmed case of SARS-CoV-2 infection - Two options, A through B: A. A person with a positive nucleic acid amplification test, regardless of clinical criteria OR epidemiological criteria; or B. Meeting clinical criteria AND/OR epidemiological criteria (See suspect case A). With a positive professional use or self-test SARS-CoV-2 Antigen-Rapid Diagnostic Test. 3. At least two moderate symptoms from the same symptom cluster or one severe cluster-associated symptom identified via the Cluster Targeted COVID-19 Symptom Questions (CTCSQ), with participant identifying new symptoms since COVID-19 illness and having persisted for at least 12 weeks 4. Meeting PRO Symptom Cluster criteria for at least one Symptom Cluster 5. Willing and able to provide informed consent, complete the surveys, clinical assessments, and return for all of the necessary follow-up visits Exclusion Criteria: An individual who meets any of the following criteria will be excluded from participation in this study. Refer to appendices for additional appendix-level criteria: 1. Known active acute SARS-CoV-2 infection ≤ 4 weeks from consent 2. Known severe anemia, defined as \< 8 g/dL 3. Meeting the following symptom cluster exclusion for all eligible clusters\*: a. Cognitive dysfunction: known stroke that resulted in cognitive impairment within 3 months of enrollment b. Autonomic dysfunction: atrial fibrillation or significant cardiac arrhythmia, more than moderate alcohol consumption\*\*, pre-existing sustained severe hypertension (BP\> 180/110 mmHg in the sitting position) c. Exercise intolerance: i. any of the following within 4 weeks of consent - an acute myocardial infarction or unstable angina, uncontrolled arrhythmias causing symptoms or hemodynamic compromise, acute myocarditis or pericarditis, uncontrolled acutely decompensated heart failure (acute pulmonary edema), acute pulmonary embolism, suspected dissecting aneurysm, severe hypoxemia at rest, any acute or chronic disorder that may affect exercise performance ii. if the participant is aggravated by exercise (e.g., infection, thyrotoxicosis, unable to cooperate) \*Participants who are eligible for \> 1 cluster must meet all inclusion and no exclusion criteria for an individual symptom cluster. If not, the participant will be excluded from that individual symptom cluster. \*\* Defined as greater than 2 drinks a day for men and 1 drink a day for women. A drink is equivalent to 12 ounces of beer (5% alcohol content), 8 ounces of malt liquor (7% alcohol content), 5 ounces of wine (12% alcohol content), 1.5 ounces or a "shot" of 80-proof (40% alcohol content) distilled spirits or liquor (e.g., gin, rum, vodka, whiskey). 21 4. Known diagnosis of chronic Lyme disease with persistent symptoms, sequelae, or related therapy 5. Any non-marijuana illicit drug use within 30 days of informed consent 6. Current or recent use (within the last 14 days) of study intervention\* 7. Known allergy/sensitivity or any hypersensitivity to components of the study intervention (s) or control\* 8. Known contraindication(s) to study intervention(s), 9. Inability to discontinue symptomatic medications for the identified time periods 10. Moderate or severe immunocompromised patients, such as those described in the NIH COVID-19 Treatment Guidelines (https://www.covid19treatmentguidelines.nih.gov/ special populations/immunocompromised/) 11. Currently enrolled in another clinical trial outside this platform protocol or another study intervention appendix in this platform protocol\*\*\* \*\*\*Participants may re-enroll in the trial for a different study intervention appendix if the participant has completed an appropriate washout period and efficacy has been determined for the appendix in which the participant was previously enrolled. 12. Any condition that would make the participant, in the opinion of the investigator, unsuitable for the study * If only one study intervention appendix is open at the time of enrollment. If multiple study intervention appendices are open, a participant may be excluded from any study intervention appendix based on contraindications listed in the study intervention appendix, current use of study intervention, or known allergy/sensitivity/hypersensitivity and still remain eligible for the remaining study intervention appendices.

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Conditions

The condition(s) this trial relates to.

long COVID-19

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

Long COVID Long COVID19

Contacts and locations

Locations

Atlanta VA Medical Center

Atlanta, Georgia, 45267, United States
Avera McKennan Hospital & University Health Center

Sioux Falls, South Dakota, 57108, United States
Beth Israel Deaconess Medical Center

Boston, Massachusetts, 02215, United States
Boston Medical Center

Boston, Massachusetts, 02118, United States
Brigham and Womens Hospital

Boston, Massachusetts, 02115, United States
Cedars Sinai Medical Center

Los Angeles, California, 90048, United States
Cleveland Clinic

Cleveland, Ohio, 44195, United States
Clinical Trials Center of Middle Tennessee

Franklin, Tennessee, 37067, United States
Dartmouth Hitchcock Medical Center

Lebanon, New Hampshire, 03756, United States
Duke Clinical and Translational Science Institute

Kannapolis, North Carolina, 28081, United States
East Carolina University

Greenville, North Carolina, 27834, United States
Emory Health Care

Decatur, Georgia, 30030, United States
Froedtert Hospital-Medical College of Wisconsin

Milwaukee, Wisconsin, 53226, United States
Grady Memorial Hospital

Atlanta, Georgia, 30303, United States
Hispanic Alliance for Clinical and Translational Research, Univ of Puerto Rico

San Juan, 00935, Puerto Rico
Hoag Memorial Hospital

Newport Beach, California, 92663, United States
Houston Methodist Hospital

Houston, Texas, 77030, United States
Howard University Hospital

Washington D.C., District of Columbia, 20060, United States
Icahn School of Medicine at Mount Sinai

New York, New York, 10029, United States
Jadestone Clinical Research, LLC

Silver Spring, Maryland, 20904, United States
Johns Hopkins Hospital

Baltimore, Maryland, 21287, United States
Kaiser Permanente Southwood

Atlanta, Georgia, 30305, United States
Koch Family Medicine

Morton, Illinois, 61550, United States
Lakeland Regional Medical Center

Lakeland, Florida, 33805, United States
Lillestol Research, LLC

Fargo, North Dakota, 58104, United States
Los Angeles Biomedical Institute at Harbor-UCLA Medical Center

Torrance, California, 90502, United States
Mayo Clinic

Rochester, Minnesota, 55905, United States
Methodist Medical Center of Illinois

Peoria, Illinois, 61603, United States
MetroHealth System

Cleveland, Ohio, 44109, United States
Morehouse School of Medicine

Atlanta, Georgia, 30310, United States
NYU Langone Health/Brooklyn Hospital

Brooklyn, New York, 11220, United States
North Shore University Health System

Evanston, Illinois, 60201, United States
Northwestern Memorial Hospital

Chicago, Illinois, 60611, United States
Oklahoma Clinical and Translational Science Institute

Oklahoma City, Oklahoma, 73104, United States
Oregon Health and Science University

Portland, Oregon, 97239, United States
Providence Medical Research Center

Spokane, Washington, 99204, United States
Rush University Medical Center

Chicago, Illinois, 60612, United States
Rutgers University-Robert Wood Johnson Medical School

New Brunswick, New Jersey, 08901, United States
Saint Francis Medical Center

Peoria, Illinois, 61637, United States
Sentara Norfolk General Hospital

Norfolk, Virginia, 23507, United States
St. Lawrence Health Medical Campus

Canton, New York, 13676, United States
Stanford University

Stanford, California, 94305, United States
Swedish Health Services

Seattle, Washington, 98104, United States
Tufts Medical Center

Boston, Massachusetts, 02111, United States
UPMC Presbyterian Shadyside

Pittsburgh, Pennsylvania, 15213, United States
University Hospitals Cleveland Medical Center

Cleveland, Ohio, 44106, United States
University of Alabama at Birmingham

Birmingham, Alabama, 35205, United States
University of Arizona Banner Medical Center

Tucson, Arizona, 85719, United States
University of Arizona/Banner University Medical Center Phoenix

Phoenix, Arizona, 85006, United States
University of California San Francisco General Hospital

San Francisco, California, 94110, United States
University of Cincinnati Medical Center

Cincinnati, Ohio, 45267, United States
University of Colorado

Aurora, Colorado, 80045, United States
University of Florida College of Medicine Jacksonville

Jacksonville, Florida, 32206, United States
University of Illinois at Chicago

Chicago, Illinois, 60612, United States
University of Kansas Medical Center

Kansas City, Kansas, 66160, United States
University of Kentucky Chandler Medical Center

Lexington, Kentucky, 40536, United States
University of Mississippi Medical Center

Jackson, Mississippi, 39216, United States
University of New Mexico Health Science Center

Albuquerque, New Mexico, 87106, United States
University of North Carolina

Chapel Hill, North Carolina, 27599, United States
University of Texas Health Science Center at Houston

Houston, Texas, 77030, United States
University of Texas Health Science Center at San Antonio

San Antonio, Texas, 78229, United States
University of Virginia

Charlottesville, Virginia, 22903, United States
University of Washington

Seattle, Washington, 98109, United States
Valencia Medical and Research Center

Miami, Florida, 33165, United States
Vermont Lung Center, University of Vermont

Colchester, Vermont, 05446, United States
Wake Forest University

Winston-Salem, North Carolina, 27103, United States
Washington University School of Medicine

St Louis, Missouri, 63110, United States
Weil Cornell Medicine

New York, New York, 10065, United States
West Virginia Clinical and Translational Science Institute

Morgantown, West Virginia, 26506, United States

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