Inclusion Criteria:  Male and female participants who are classically healthy having no clinically relevant abnormalities. No known or suspected hepatic impairment Stable hepatic impairment that meets the criteria for Class B of the Child-Pugh Classification  Exclusion Criteria:  Any condition possibly affecting drug absorption (eg, prior bariatric surgery, gastrectomy, ileal resection). Participants who have been vaccinated with COVID-19 vaccines within the past week of dosing A positive urine drug test, for illicit drugs, at Screening History of sensitivity reactions to ritonavir or any of the formulation components of PF-07321332 or ritonavir. eGFR <60 mL/min/1.73m2 based on the Chronic Kidney Disease-Epidemiology Collaboration (CKD-EPI) equation Aspartate aminotransferase (AST) or alanine aminotransferase (ALT) level ≥ upper limit of normal (ULN) (for healthy participants); AST or ALT > 5x ULN (for hepatic impairment participants) Albumin > ULN (for healthy participants); Prothrombin time > ULN (for healthy participants); Total bilirubin level ≥1.5 × ULN [NOTE: Participants with a history of Gilbert syndrome (and hence elevated total bilirubin) are eligible provided direct bilirubin level is ≤ ULN).