(HealthDay News) — For patients with confirmed COVID-19, nirmatrelvir-ritonavir is not associated with a shorter time to sustained alleviation of symptoms than placebo, according to a study published in the April 4 issue of the New England Journal of Medicine.

Jennifer Hammond, PhD, from Global Product Development at Pfizer in Collegeville, PA, and colleagues randomly assigned adults with confirmed COVID-19 with symptom onset in the past five days to receive nirmatrelvir-ritonavir or placebo every 12 hours for five days (654 and 634 participants, respectively). From day 1 through day 28, participants logged the presence and severity of prespecified COVID-19 signs and symptoms daily.

The researchers found that the median time to alleviation of all targeted signs and symptoms of COVID-19 was 12 and 13 days in the nirmatrelvir-ritonavir and placebo groups, respectively. Five and 10 participants in the nirmatrelvir-ritonavir and placebo groups, respectively, were hospitalized for COVID-19 or died from any cause (difference, −0.8 percentage points; 95% confidence interval, −2.0 to 0.4). The percentage of participants with adverse events was 25.8 and 24.1% for nirmatrelvir-ritonavir and placebo, respectively.

“Nirmatrelvir-ritonavir was not associated with a significantly shorter time to sustained alleviation of COVID-19 symptoms than placebo, and the usefulness of nirmatrelvir-ritonavir in patients who are not at high risk for severe COVID-19 has not been established,” the authors write.

The study was funded by Pfizer.

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