Application of nirmatrelvir-ritonavir for primary and secondary outcomes
The mean time from symptom onset or the first positive RT-PCR result to negative RT-PCR results was similar in both the treatment and control groups (16.2±5.0 vs. 16.1±6.3 days, P = 0.83, Table 2). Figure 2 displays the Kaplan-Meier survival curve for the primary outcome. No correlation was observed between the time to conversion of RT-PCR results and patients’ age, clinical classification, concurrent medication usage, or prior vaccination in the analysis of individuals treated with nirmatrelvir-ritonavir, except in the case of the usage of antibiotics (Figure 4). Following the appearance of symptoms or the initial RT-PCR confirmation, 92% of nirmatrelvir-ritonavir was administered within 14 days, while 82% and 64% were taken within 10 and 7 days respectively (Figure 3). Hence, the subgroup analysis was further stratified based on the time interval between the administration of nirmatrelvir-ritonavir and the onset of symptoms or the first positive RT-PCR test. Patients who received nirmatrelvir-ritonavir within 10 days of experiencing symptoms demonstrated quicker conversion of RT-PCR results compared to the control group that was matched (Figure 5).
No significant difference was found between the two groups in the percentage of patients who tested negative for respiratory SARS-CoV-2 using RT-PCR 15 days after the onset of symptoms (47.2% vs 50.0%, P=0.53). Additionally, the two groups did not differ significantly with respect to the progression to more severe conditions, such as turning to critically ill (1.9% vs 1.9%, P = 1), need for mechanical ventilation (0.3% vs 1.5%, P = 0.21), and the need for oxygen therapy (2.5% vs 3.4%, P = 0.64).