Baseline characteristics of the patients
Upon hospital admission, patients’ baseline characteristics were
gathered, including sex, age, clinical classification(i.e., severity of
symptoms), underlying health conditions, risk factors of developing
severe illness, and immunization record. The number of days from the
onset of symptoms or a positive RT-PCR test to hospitalization and to
initiation of treatment were calculated. Within 2 days of being admitted
to the hospital, respiratory samples
were obtained from the upper respiratory tract of patients using a
nasopharyngeal swab. The samples underwent testing using a real-time
fluorescence quantitative RT-PCR method to detect the presence of the
SARS-CoV-2 virus. The targets for the RT-PCR assay were open reading
frame 1ab (ORF), nucleocapsid protein gene (N gene) and envelope protein
gene (E gene). All the targets were recorded with the cycle threshold
(Ct) value, which represents the number of cycles required to amplify
the viral nucleic acid to a detectable level. A Ct value below 35 for
ORF, N gene or E gene was used to define a positive sample of
SARS-CoV-2[17].
Intervention and control
Every patient was provided with standard care, which involved resting in
bed, monitoring vital signs, measuring oxygen saturation, conducting
routine blood chemistry and urine analysis, examining biochemical
indicators such as liver and myocardial enzymes and renal function,
assessing coagulation parameters, analyzing arterial blood gas,
conducting chest imaging and cytokine detection, and administering
oxygen therapy if necessary. Individuals in the intervention cohort were
administered nirmatrelvir at a dosage of 300 mg alongside ritonavir at a
dosage of 100 mg, twice a day, for a duration of 5 days. Alternatively,
if patients’ eGFR ranged from 30-59 mL/min per 1.73 m², the dosage of
nirmatrelvir was reduced to 150 mg while ritonavir remained at 100 mg.
Patients in the control group only obtained standard care and were not
administered nirmatrelvir-ritonavir. Patients in both groups did not
receive any other medications specifically for COVID-19, such as
remdesivir or monoclonal antibodies.