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.

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.

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.

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.