A Study to Learn About the Study Medicines (Nirmatrelvir Plus Ritonavir) in People Aged 12 Years or Older With COVID-19 and a Compromised Immune System

NP swab was collected by healthcare professional (HCP) from participants and were sent to the central laboratory for viral RNA level testing real-time reverse transcriptase-polymerase chain reaction(RT-PCR). Sustained was defined as NP swab SARS-CoV-2 RNA level not >=2.0 log10 per milliliter (copies/mL) at any study visit (through Day 44) following the first study visit where the participant's NP swab SARS-CoV-2 RNA level <LLOQ (<2.0 log10 copies/mL).

An NP swab was collected by HCP from participants and were sent to the central laboratory for viral RNA level testing RT-PCR. The LLOQ is <2.0 log10 copies/mL. Kaplan-Meier method was used for analysis. Time (days) to first NP swab SARS-CoV-2 RNA<LLOQ (event) was calculated as (First Event Date) - (First Dose Date) +1.

An NP swab was collected by HCP from participants and were sent to the central laboratory for viral RNA level testing RT-PCR. Sustained was defined as NP swab SARS-CoV-2 RNA level not >=2.0 log10 copies/mL at any study visit (through Day 44) following the first study visit where the participant's NP swab SARS-CoV-2 RNA level < LLOQ. The LLOQ is <2.0 log10 copies/mL. Time (days) to first sustained NP swab SARS-CoV-2 RNA<LLOQ (event) was calculated as (First Event Date) - (First Dose Date) +1.

A 6-mL blood sample was collected for adult and pediatric participants and was analyzed to measure SARS-CoV-2 RNA <LLOQ in Plasma by RT-PCR. The LLOQ is <2.0 log10 copies/mL.

An NP swab was collected by HCP from adult and pediatric participants and were sent to the central laboratory for viral RNA level testing RT-PCR. The LLOQ is <2.0 log10 copies/mL.

An NP swab was collected by HCP from adult and pediatric participants and were sent to the central laboratory for viral RNA level testing RT-PCR.

A 6-mL blood sample was collected for adult and pediatric participants and was analyzed to measure SARS-CoV-2 RNA by RT-PCR.

Rebound in SARS-CoV-2 RNA level in NP swabs at follow up (ie, any study visit after end of treatment through Day 44) was defined as a half (0.5) log10 copies/mL increase or greater in SARS-CoV-2 RNA level relative to end of treatment SARS-CoV-2 RNA level based on treatment regimen, with a follow-up viral RNA level >= 2.5 log10 copies/mL.

An adverse event (AE) was any untoward medical occurrence that did not necessarily have a causal relationship with study treatment. TEAE was an AE that occurred after initiation of study treatment that was not present at the time of treatment start or an AE that increased in severity after the initiation of medication, if the event was present at the time of treatment start emerges. SAE was an AE resulting in any of the following outcomes or considered medically significant: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly or birth defect.

Hospitalization >24 h is defined as >24h of acute care in a hospital or similar acute care facility, including emergency rooms or temporary facilities instituted to address medical needs of those with severe COVID-19. This included specialized acute medical care unit within an assisted living facility or nursing home. This did not include hospitalization for the purposes of public health and/or clinical trial execution.

Death due to any cause through week 24 was considered. Kaplan-Meier method was used for evaluation.

COVID-19 related hospitalization is defined as >24h of acute care in a hospital or similar acute care facility, including emergency rooms or temporary facilities instituted to address medical needs of those with severe COVID-19. This included specialized acute medical care unit within an assisted living facility or nursing home. This did not include hospitalization for the purposes of public health and/or clinical trial execution.

Invasive mechanical ventilation or ECMO were types of oxygen support received in hospital.

Hospitalization >24 hours is defined as >24h of acute care in a hospital or similar acute care facility, including emergency rooms or temporary facilities instituted to address medical needs of those with severe COVID-19.

Symptoms alleviation through day44 of each targeted COVID-19 sign/symptom was defined as first time when each targeted symptom scored as moderate/severe at study entry are scored as mild or absent and a targeted symptom scored mild or absent at study entry are scored as absent.COVID-19 targeted signs/symptoms were muscle or body aches,shortness of breath(SOB)or difficulty breathing,chills or shivering, cough,diarrhea,feeling hot or feverish,headache,nausea,stuffy or runny nose,sense of smell,sense of taste,sore throat,low energy or tiredness, vomit.

Symptoms resolution through day 44 of each targeted COVID-19 sign/symptom was defined as the first time when each targeted symptom scored as mild, moderate or severe at study entry are scored as absent. COVID -19 targeted signs/symptoms were muscle or body aches, SOB or difficulty breathing, chills or shivering, cough, diarrhoea, feeling hot or feverish, headache, nausea, stuffy or runny nose, sense of smell, sense of taste, sore throat, low energy or tiredness, vomit.

COVID-19 targeted signs/symptoms were muscle or body aches, SOB or difficulty breathing, chills or shivering, cough, diarrhea, feeling hot or feverish, headache, nausea, stuffy or runny nose, sense of smell, sense of taste, sore throat, low energy or tiredness, vomit.