18 and older, any sex, with COVID-19. Patients with the condition only — healthy volunteers not accepted.
Results — posted to ClinicalTrials.gov
Per-arm endpoint measurements with 95% confidence intervals where reported. Source: trial results section.
Time to Sustained Alleviation of Overall COVID-19 Signs and Symptoms Through Day 28Primary· From Day 1 to Day 28
Sustained alleviation of targeted COVID-19 signs/symptoms was defined as the event occurring on the first 4 consecutive days when all symptoms scored as moderate or severe at the time of enrollment were scored as mild or absent and those scored mild or absent at the time of enrollment were scored as absent. Missing severity at baseline was considered as mild. Time to sustained alleviation of all targeted COVID-19 signs and symptoms through Day 28, was calculated as time (days) from start of study intervention or placebo (Day 1) until sustained alleviation of all targeted COVID-19 associated si
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
12.000
11.000 – 13.000
Placebo
13.000
12.000 – 14.000
Number of Participants With Treatment Emergent Adverse Events (TEAEs), Serious AEs and AEs Leading to Study and Study Drug DiscontinuationSecondary· From start of study intervention (Day 1) up to Day 34
An AE was defined as any untoward medical occurrence in a participant or clinical study participant temporally associated with the use of study intervention, whether or not considered related to the study intervention. An SAE was defined as any untoward medical occurrence at any dose that resulted in any of the following outcomes: death; life-threatening ; required inpatient hospitalization or prolongation of existing hospitalization; persistent or significant disability/incapacity ; congenital anomaly/birth defect; or that was considered as an important medical event. TEAEs were defined as ev
TEAEs
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
169
Placebo
153
SAEs
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
8
Placebo
13
AEs led to discontinuation of study
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
0
Placebo
1
AEs led to discontinue study intervention and continued study
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
16
Placebo
5
Percentage of Participants With COVID-19 Related Hospitalization or Death From Any Cause Through Day 28Secondary· From Day 1 to Day 28
Percentage of participants with COVID-19 related hospitalization or death from any cause during the first 28 days of the study was estimated using the Kaplan-Meier (KM) method.
COVID-19 hospitalization
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
0.765
Placebo
1.577
Death
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
0
Placebo
0.158
Percentage of Participants With Death Through Week 24Secondary· From Day 1 to Week 24
Percentage of participants with death (all-cause) event were reported in this outcome measure.
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
0
Placebo
0.2
Number of COVID-19 Related Medical Visits Per Day Through Day 28Secondary· From Day 1 to Day 28
Number of COVID-19 related medical visits per day were reported in this outcome measure.
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
0.0010
0.0005 – 0.0019
Placebo
0.0020
0.0010 – 0.0038
Duration of Hospitalization and Intensive Care Unit (ICU) Stay Through Day 28Secondary· From Day 1 to Day 28
Hospitalization
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
0.049
± 0.591
Placebo
0.181
± 1.787
ICU
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
0.000
± 0.000
Placebo
0.065
± 1.004
Percentage of Participants With Severe Signs and Symptoms of COVID-19 Through Day 28Secondary· From Day 1 to Day 28
Participants recorded a daily severity rating of their symptom severity over the past 24 hours based on a 4-point scale in which 0 was reported if no symptoms were present; 1 if mild; 2 if moderate; and 3 if severe. A participant with severe score for any targeted symptoms post-baseline was counted as severe. Vomiting and diarrhea each was rated on a 4-point frequency scale where 0 was reported for no occurrence, 1 for 1 to 2 times, 2 for 3 to 4 times, and 3 for 5 or greater. Sense of smell and sense of taste each be rated on a 3-point Likert scale where 0 was reported if the sense of smell/ta
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
19.136
Placebo
21.643
Time to Sustained Resolution of Overall COVID-19 Signs and Symptoms Through Day 28Secondary· From Day 1 to Day 28
Sustained resolution was defined as when targeted symptoms are scored as absent for 4 consecutive days. The first day of the 4 consecutive-day period was considered the first event date.
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
15.000
14.000 – 16.000
Placebo
16.000
15.000 – 17.000
Time to Sustained Alleviation of Each COVID-19 Signs and Symptoms Through Day 28Secondary· From Day 1 to Day 28
Sustained alleviation of targeted COVID-19 signs/symptoms was defined as the event occurring on the first 4 consecutive days when all symptoms scored as moderate or severe at the time of enrollment were scored as mild or absent and those scored mild or absent at the time of enrollment were scored as absent. Missing severity at baseline was treated as mild. Time to sustained alleviation of all targeted COVID-19 signs and symptoms through Day 28, was calculated as time (days) from start of study intervention or placebo (Day 1) until sustained alleviation of all targeted COVID-19 associated signs
Muscle or body aches
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
5.000
4.000 – 6.000
Placebo
5.000
4.000 – 6.000
Shortness of breath or difficulty breathing
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
5.000
4.000 – 6.000
Placebo
6.000
5.000 – 7.000
Chills or shivering
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
3.000
3.000 – 4.000
Placebo
3.000
3.000 – 4.000
Cough
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
7.000
6.000 – 8.000
Placebo
8.000
7.000 – 9.000
Diarrhea
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
6.000
5.000 – 9.000
Placebo
4.000
3.000 – 6.000
Feeling hot or feverish
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
3.000
NA – NA
Placebo
4.000
3.000 – 4.000
Headache
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
5.000
4.000 – 5.000
Placebo
5.000
5.000 – 6.000
Nausea
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
4.000
3.000 – 5.000
Placebo
4.000
3.000 – 5.000
Time to Sustained Resolution of Each COVID-19 Signs and Symptoms Through Day 28Secondary· From Day 1 to Day 28
Sustained resolution was defined as when targeted symptoms are scored as absent for 4 consecutive days. The first day of the 4 consecutive-day period was considered the first event date. In this outcome measure time to sustained resolution is reported consolidated for each COVID-19 signs and symptoms.
Muscle or body aches
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
8.000
7.000 – 9.000
Placebo
9.000
7.000 – 10.000
Shortness of breath or difficulty breathing
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
7.000
5.000 – 7.000
Placebo
8.000
7.000 – 11.000
Chills or shivering
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
4.000
3.000 – 5.000
Placebo
5.000
4.000 – 6.000
Cough
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
11.000
10.000 – 12.000
Placebo
12.000
11.000 – 13.000
Diarrhea
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
6.000
6.000 – 8.000
Placebo
5.000
4.000 – 6.000
Feeling hot or feverish
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
4.000
3.000 – 5.000
Placebo
5.000
5.000 – 6.000
Headache
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
7.000
7.000 – 9.000
Placebo
9.000
8.000 – 10.000
Nausea
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
6.000
4.000 – 7.000
Placebo
5.000
4.000 – 7.000
Percentage of Participants With Progression to Worsening Status of COVID-19 Signs and SymptomsSecondary· From Day 1 to Day 28
Participants recorded a daily severity rating of their symptom severity over the past 24 hours based on a 4-point scale in which 0 was reported if no symptoms were present; 1 if mild; 2 if moderate; and 3 if severe. Vomiting and diarrhea was rated on a 4-point frequency scale where 0 is reported for no occurrence, 1 (mild) for 1 to 2 times, 2 (moderate) for 3 to 4 times, and 3 (severe) for 5 or greater. Progression to a worsening status for any targeted symptom was based up on increasing severity (i.e. the first time any targeted symptoms worsened after treatment relative to baseline).
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
75.463
Placebo
78.515
Percentage of Participants With Resting Peripheral Oxygen Saturation Greater Than or Equal to (>=) 95% at Day 1 and Day 5Secondary· Day 1 and Day 5
Percentage of participants with a resting peripheral oxygen saturation \>=95% were reported in this outcome measure.
Day 1
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
62.500
Placebo
67.857
Day 5
Group
Value
95% CI
Nirmatrelvir 300 mg + Ritonavir 100 mg
94.671
Placebo
93.212
Adverse events — posted to ClinicalTrials.gov
Time frame: SAEs and Non-SAEs: From Day 1 to Week 24; All-cause mortality: till Week 24.
Reporting threshold: 1%.
Adverse-event reports describe events observed during the trial — not all are caused by the drug.
Nirmatrelvir 300 mg + Ritonavir 100 mg
Serious: 8/654 (1%)
Deaths: 0/654
Placebo
Serious: 13/634 (2%)
Deaths: 1/634
Serious adverse events (12 terms)
Reaction
System
Nirmatrelvir 300 mg + Rito…
Placebo
COVID-19 pneumonia
Infections and infestations
—
—
Pneumonia
Infections and infestations
—
—
COVID-19
Infections and infestations
—
—
Pneumonia aspiration
Infections and infestations
—
—
Sepsis
Infections and infestations
—
—
Creatinine renal clearance decreased
Investigations
—
—
Hepatic enzyme increased
Investigations
—
—
Electrolyte imbalance
Metabolism and nutrition disorders
—
—
Colon cancer metastatic
Neoplasms benign, malignant and unspecified (incl cysts and polyps)
The primary hypothesis to be tested is whether or not there is a difference in time to sustained alleviation of all targeted COVID-19 signs and symptoms through Day 28 between PF-07321332/ritonavir and placebo.
Publications & conference data
8 peer-reviewed publications reference this trial (live from Europe PMC):
NCT05263895 — Relative Bioavailability Study of 4 Different Formulations of PF-07321332 Relative to the Commercial Tablet Formulation
· Phase 1
· completed
NCT05047601 — A Study of a Potential Oral Treatment to Prevent COVID-19 in Adults Who Are Exposed to Household Member(s) With a Confir
· Phase 2, PHASE3
· completed
NCT05005312 — Study to Estimate the Effects of Hepatic Impairment on the Pharmacokinetics (PK) of PF-07321332
· Phase 1
· completed
NCT04960202 — EPIC-HR: Study of Oral PF-07321332/Ritonavir Compared With Placebo in Nonhospitalized High Risk Adults With COVID-19
· Phase 2, PHASE3
· completed
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Publications: Europe PMC API search by NCT ID, retrieved 10 June 2026
Drug + disease cross-links: matched in real time against Drug Landscape's normalised drug + company + condition tables
Sponsor: as reported to ClinicalTrials.gov by Pfizer
Last refreshed: 14 August 2023
Drug Landscape aggregates and links these public records for informational use only. Always verify against the primary source before clinical or regulatory decisions. Canonical URL: https://druglandscape.com/trial/NCT05011513.