A large study yesterday in the International Journal of Infectious Diseases shows that, if prescribed within 5 days of confirmed infection, Paxlovid (nirmatrelvir-ritonavir) is more effective in protecting against all-cause mortality and severe COVID-19 in adults than is molnupiravir, another antiviral drug.
The study was conducted in Hong Kong in 2022. Researchers said they also found no significant difference between CoronaVac (made by Sinovac Biotech) and Comirnaty (Pfizer-BioNTech) vaccines in the effectiveness of reducing all-cause mortality and progression to severe COVID-19.
The authors of the study assessed 61,105 hospitalized adult patients in Hong Kong who had confirmed SARS-CoV-2 infection from March 16 to December 31, 2022. During the study period, Omicron BA.2 and BA.5 subvariants were dominant.
The primary outcome was all-cause 28-day mortality from a confirmed COVID-19 infection. A secondary outcome was the development of severe illness, defined as requiring intubation, intensive care unit admission, extracorporeal membrane oxygenation, shock, or oxygen supplement of at least three liters per minute.
A total of 16,068 (26.3%) of patients were treated with molnupiravir, and 18,113 (29.6%) were treated with Paxlovid. About 44% of patients did not receive antiviral treatments.
Efficacy depends on early treatment
The molnupiravir users, Paxlovid users, and controls had cumulative fatal incidences of 1,404, 245, and 2,732, respectively, and severe case incidences of 1,766, 794, and 2,848, respectively.
Paxlovid use within 5 days of confirmed infection for those 18 to 59 years was associated with a significantly lower risk of all-cause mortality (hazard ratio [HR], 0.48; 95% confidence interval, 0.25 to 0.92).
Molnupiravir was also associated with significantly lower risks of all-cause mortality and progression to severe COVID-19 for patients aged 60 to 79 years (mortality and severe case HRs of 0.65 and 0.69, respectively).
"Given prescriptions were made within five days of confirmed infection, the use of nirmatrelvir-ritonavir was associated significantly lower risks of all-cause mortality and progression to severe COVID-19 than those of molnupiravir across all three age groups," the authors wrote. The third age-group assessed was people 80 and older.
The use of nirmatrelvir-ritonavir was associated significantly lower risks of all-cause mortality and progression to severe COVID-19 than those of molnupiravir.
No significant benefit was found for oral antivirals prescribed beyond 5 days of confirmed infection, the authors said. Both Comirnaty and CoronaVac were found to be equally effective in preventing severe outcomes, in all age-groups.
