Nirmatrelvir-ritonavir is approved for coronavirus disease 2019 (COVID-19) but not initially recommended in patients with severe renal impairment. Increasing observational data have shown the feasibility of dose-adjusted nirmatrelvir-ritonavir administration in patients with estimated glomerular filtration rate lower than 30 ml/min/1.73 m^2. The study is planned to assess the safety, clinical and virologic outcomes of early oral nirmatrevir-ritonavir treatment of COVID-19 in patients with stage 4 and 5 chronic kidney disease.

The objectives of the study are to evaluate the safety and clinical and virologic outcomes of dose-adjusted nirmatrelvir-ritonavir in patients with eGFR lower than 30 ml/min/1.73 m^2. Patients with eGFR greater than 30 ml/min/1.73 m2 and prescribed nirmatrelvir-ritonavir will be used for comparison.

In the single-centre study, patients with stage 4 and 5 chronic kidney disease prescribed early treatment dose-adjusted nirmatrelvir-ritonavir will be assessed for the primary endponts of adverse events during or after treatment with nirmatrelvir-ritonavir (starting on or before day 30), serious adverse events and adverse events leading to discontinuation of nirmatrelvir-ritonavir.

Inclusion Criteria:

• Aged 18 and above.
• COVID-19 infection and symptom onset no more than 5 days, with or without prior vaccination.
• WHO CPS 1-4
• Indicated for nirmatrelvir-ritonavir treatment

Exclusion Criteria:

• Patients cannot swallow capsules or adhere to protocol.
• Severe COVID-19 disease, including patients who require oxygen supplement therapy
• Significant hypersensitivity to nirmatrelvir, ritonavir, or any component of the formulation
• Patients require co-administration of drugs that are highly dependent on CYP3A4 for clearance and cannot be omitted during the treatment period

This is a single centre study of 100 adult patients treated with nirmatrelvir-ritonavir for early COVID-19 disease in the omicron era.