The DEFEND trial will be the world's first clinical trial to study the effectiveness of Paxlovid or Veklury in the prevention of cardiovascular post-acute sequelae of SARS-CoV-2 among hospitalized adults. Additionally, this pilot study will inform the design and conduct of a future full-scale multi-centre trial by testing the feasibility and accuracy of this study design.
View on ClinicalTrials.gov ↗Last updated 07 October 2026 from ClinicalTrials.gov. Trial statuses are refreshed automatically; check the registry record for the latest status and contact details.
9 trials3 open to enrolment1 active, not recruiting5 completed
All interventional trials in our ClinicalTrials.gov extract that list Paxlovid (Nirmatrelvir/Ritonavir) as an intervention, across Long COVID / PASC (8), Unspecified / Overlap (1). 3 are currently open to enrolment and 5 have completed. Read the OSMF evidence profile for Paxlovid (Nirmatrelvir/Ritonavir) for literature, mechanism and dosing context.
Intervention names are normalised from the registry's own arm labels, so the same compound can appear under a brand name, a generic name or a combination; check the full agent index for related entries.
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Not medical advice. This page is an automatically compiled index of entries on ClinicalTrials.gov. Listing here is not an endorsement of any trial, sponsor or treatment, and trial status can change between our refreshes. Always confirm details on ClinicalTrials.gov and discuss participation with your own clinician.
Recruiting (2)
Investigators are conducting a study on alternative treatments for patients who have received an current or previous positive COVID-19 diagnosis with mild-serve symptoms or undiagnosable condition after testing positive for severe acute COVID-19 infection and are experiencing long-haul symptoms.
View on ClinicalTrials.gov ↗Not yet recruiting (1)
The purpose of this research study is to test if the combination of three drugs, valacyclovir, celecoxib, and Paxlovid will decrease the symptoms of Long COVID in adults compared to a placebo (this does not contain the medications).
View on ClinicalTrials.gov ↗Active, not recruiting (1)
The goal of this clinical trial is to compare treatment with oral Paxlovid (nirmatrelvir/ritonavir) and placebo for acute COVID-19 as an intervention to prevent long-COVID (post-COVID-19 condition) in adults aged 18-64 years old. The main question it aims to answer is: Does treatment with Paxlovid for acute COVID-19 reduce the prevalence of long-COVID compared to placebo.
View on ClinicalTrials.gov ↗Completed (5)
RECOVER-VITAL: Platform Protocol, Appendix to Measure the Effects of Paxlovid on Long COVID Symptoms
This is an appendix of master protocol (NCT05595369) designed to be flexible so that it is suitable for a wide range of settings within health care systems and in community settings where it can be integrated into COVID-19 programs and subsequent treatment plans.
View on ClinicalTrials.gov ↗This study is a platform protocol designed to be flexible so that it is suitable for a wide range of settings within health care systems and in community settings where it can be integrated into COVID-19 programs and subsequent treatment plans.
View on ClinicalTrials.gov ↗The purpose of this study is to compare whether being treated with nirmatrelvir plus ritonavir for 15 days works better than being treated with placebo plus ritonavir to reduce severe symptoms of Long Covid. Participants will have 5 planned visits to the study clinic over 15 weeks and will take the drug (or placebo) for the first 15 days.
View on ClinicalTrials.gov ↗The purpose of this study is to investigate the efficacy of orally administered nirmatrelvir/ritonavir compared with placebo/ritonavir to improve quality of life in non-hospitalized adult participants suffering from post-acute COVID-19 syndrome.
View on ClinicalTrials.gov ↗This decentralized trial is a Phase 2, 1:1 randomized, double-blind, superiority, placebo-controlled study in an anticipated 100 non-hospitalized highly symptomatic adult participants with long COVID. It seeks to determine the efficacy, safety, and tolerability of 15 days of Paxlovid (nirmatrelvir/ritonavir), an anti-viral agent, compared with placebo plus ritonavir.
View on ClinicalTrials.gov ↗Frequently asked questions
How do I join a clinical trial?
Open the trial's ClinicalTrials.gov record (the "View on ClinicalTrials.gov" button), read the Eligibility Criteria and Contacts and Locations sections, and contact the study team listed there. Trials only enrol at the sites shown in the record, so check whether a site is near you or whether the study is remote/decentralised. Your own clinician can help you judge whether a trial is a sensible option and may need to provide medical records.
What do the trial phases mean?
Early Phase 1 / Phase 1 studies test safety and dosing in a small group. Phase 2 studies look for a signal of benefit in a larger group and keep checking safety. Phase 3 studies are large confirmatory trials designed to show whether a treatment works well enough for approval. Phase 4 studies follow approved treatments after they reach the market. "Phase not applicable" is used by the registry for behavioural, device, rehabilitation and other non-drug interventions.
Does the Open Source Medicine Foundation run these trials?
No. OSMF does not sponsor, run or recruit for any trial on this page. We compile public registry entries from ClinicalTrials.gov so patients and clinicians can find them in one place. For questions about a specific study, contact the sponsor or study team listed on its ClinicalTrials.gov record.
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We summarise newly registered post-viral trials and notable results on the OSMF Substack.
Subscribe on SubstackCite this page
Open Source Medicine Foundation. Paxlovid (Nirmatrelvir/Ritonavir) clinical trials for Long COVID, ME/CFS and post-viral illness (9 trials, updated October 2026). Research Tracker, 07 October 2026.
Underlying dataset (JSON, CC BY 4.0):
Open Source Medicine Foundation. Paxlovid (Nirmatrelvir/Ritonavir) clinical trials for Long COVID, ME/CFS and post-viral illness (9 trials, updated October 2026). Research Tracker, 07 October 2026.
https://research.opensourcemed.info/trials/by-agent/paxlovid-nirmatrelvir-ritonavir.htmlUnderlying dataset (JSON, CC BY 4.0):
https://research.opensourcemed.info/data/clinical_trials/clinical_trials_current.json. Source records: ClinicalTrials.gov.Related: all agents · recruiting Long COVID trials · recruiting ME/CFS trials · open in trial finder.