The purpose of this study is to learn about the safety and effects of nirmatrelvir/ritonavir for the potential treatment of COVID-19 rebound. The study is seeking participants who: - Have completed treatment with nirmatrelvir/ritonavir - Have a rebound in COVID-19 symptoms - Are SARS-CoV-2 (COVID-19) positive All study medications will be taken 2 times a day by mouth for 5 days. The first dose of study medication is taken at the study clinic and the rest at home. We will examine the experiences of people receiving the study medicines to those who do not. This will help us determine if the study medicines are safe and effective. People taking part will be in this study for about 24 weeks. Enrolled participants will need to visit the study clinic at least 8 times during the study.



Eligible Ages
Over 12 Years
Eligible Genders
Accepts Healthy Volunteers

Inclusion Criteria

  • Documentation of nirmatrelvir/ritonavir treatment with patient-reported 100% compliance. Symptom alleviation or resolution in COVID-19 signs/symptoms followed by a worsening (rebound) of signs/symptoms after completing an initial 5-day course of nirmatrelvir/ritonavir - Onset of rebound in COVID-19 symptoms within 2 weeks (14 days) after the completion of the initial 5-day course of nirmatrelvir/ritonavir. - Onset of rebound in signs/symptoms attributable to COVID-19 within 48 hours prior to randomization and ≥1 sign/symptom attributable to COVID-19 present on the day of randomization. - SARS-CoV-2 infection as determined by rapid antigen testing within 24 hours prior to randomization - At least 1 characteristic or underlying medical condition associated with an increased risk of developing severe illness from COVID-19.

Exclusion Criteria

  • Current need for hospitalization, hospitalized for the COVID-19 infection or anticipated need for hospitalization within 24 hours after randomization - History of severe chronic liver disease - Receiving dialysis or have known age-specific estimated glomerular filtration rate (eGFR) or estimated creatinine clearance (eCrCl) <30 mL/min/1.73 m2 at screening as measured by a serum creatinine point of care device - Oxygen saturation of <92% on room air obtained at rest within 24 hours prior to randomization - Immunocompromised. - Current use of any prohibited concomitant medication(s) - Females who are pregnant and <14 weeks gestation

Study Design

Phase 2
Study Type
Intervention Model
Parallel Assignment
Primary Purpose
Triple (Participant, Care Provider, Investigator)

Arm Groups

ArmDescriptionAssigned Intervention
nirmatrelvir plus ritonavir for 5 days
Nirmatrelvir (2 tablets) plus ritonavir (1 capsule) will be given by mouth every 12 hours for 5 days
  • Drug: nirmatrelvir
    Participants will receive 2 tablets of nirmatrelvir every 12 hours
  • Drug: ritonavir
    Participants will receive 1 capsule of ritonavir every 12 hours
placebo plus ritonavir for 5 days
placebo (2 tablets) plus ritonavir (1 capsule) will be given by mouth every 12 hours for 5 days
  • Drug: ritonavir
    Participants will receive 1 capsule of ritonavir every 12 hours
  • Drug: placebo for nirmatrelvir
    Participants will receive 2 tablets of placebo for nirmatrelvir every 12 hours. A placebo does not have any medicine in it but looks just like the medicine being studied.

Recruiting Locations

More Details



Study information shown on this site is derived from ClinicalTrials.gov (a public registry operated by the National Institutes of Health). The listing of studies provided is not certain to be all studies for which you might be eligible. Furthermore, study eligibility requirements can be difficult to understand and may change over time, so it is wise to speak with your medical care provider and individual research study teams when making decisions related to participation.