Inclusion Criteria:

1. 18 years of age or older at screening.

2. Confirmed SARS-CoV-2 infection as determined by RAT (or other locally approved test)
collected within 2 days prior to randomization. Initial onset of symptoms
attributable to COVID-19 within 5 days prior to the day of randomization and at
least 1 of the specified symptoms attributable to COVID-19 present on the day of
randomization.

3. Severely immunocompromised due to:

- Solid organ or islet cell transplant recipient who is receiving
immunosuppressive therapy;

- Active hematologic malignancy (eg, chronic lymphocytic lymphoma, non-Hodgkin
lymphoma, multiple myeloma, acute leukemia);

- Receipt of CAR-T-cell therapy or HCT either within 2 years of transplantation
or who are receiving immunosuppressive therapy;

- Currently receiving B-cell depleting therapies (eg, rituximab).

Exclusion Criteria:

1. Current need for supplemental oxygen for treatment of COVID-19.

2. Receiving dialysis or have known severe renal impairment within 6 months of the
screening visit

3. Active liver disease

4. History of hypersensitivity or other contraindication to any of the components of
the study interventions, as determined by the investigator

5. Suspected or confirmed concurrent active systemic infection other than COVID-19 that
may interfere with the evaluation of response to the study intervention.

6. Life expectancy less than 30 days at study entry due to an underlying condition, in
the judgement of the investigator.

7. Any medical or psychiatric condition including recent (within the past year) or
active suicidal ideation/behavior or laboratory abnormality that may increase the
risk of study participation or, in the investigator's judgment, make the participant
inappropriate for the study.

8. Has received any other antiviral for the treatment of the current COVID-19 infection

9. Current use of any prohibited concomitant medication(s) or unwillingness or
inability to use a required concomitant medication(s).

10. Current or previous administration of an investigational product (drug or vaccine)
within 30 days (or as determined by local requirement) or 5 half lives preceding the
first dose of study intervention used in this study (whichever is longer).
Authorized or products with conditional approval are not considered investigational.

11. Prior participation in this trial or any clinical trial of ibuzatrelvir.

12. Females who are pregnant, breastfeeding, or who are planning to become pregnant
within the timeframe of the study.

13. Investigator site staff directly involved in the conduct of the study and their
family members, site staff otherwise supervised by the investigator, and sponsor and
sponsor delegate employees directly involved in the conduct of the study and their
family members.