EPIC-Peds: A Study to Learn About the Study Medicine Called PF-07321332 (Nirmatrelvir)/Ritonavir in Patients Under 18 Years of Age With COVID-19 That Are Not Hospitalized But Are at Risk for Severe Disease

Inclusion criteria: * Male and female, age 0 to \< 18 years, able to swallow for some participants * Confirmed SARS-CoV-2 infection within 72 hours prior to enrollment * Initial onset of COVID-19 signs/symptoms within 5 days prior to the day of enrollment and at least 1 of the specified COVID-19 signs/symptoms present at enrollment * Has at least 1 characteristic or underlying medical condition associated with an increased risk of developing severe illness from COVID-19 Exclusion Criteria: * History of or need for hospitalization for the medical treatment of COVID-19 * Total bilirubin \>=2X upper limit of normal (ULN) (except for Gilbert's syndrome) * Receiving dialysis or have known moderate to severe renal impairment * Suspected or confirmed concurrent active systemic infection other than COVID-19 * History of hypersensitivity or other contraindication to any of the components of the study intervention * Current or expected use of any medications or substances that are highly dependent on CYP3A4 for clearance or strong inducers of cytochrome P450 (CYP)3A4 * Has received or is expected to receive antibody treatment, antiviral treatment or convalescent COVID-19 plasma * Participating in another interventional clinical study with an investigational compound or device, including those for COVID-19 through the study follow up * Females who are pregnant or breastfeeding