Molnupiravir, Nirmatrelvir-Ritonavir Reduces Hospitalization Risk in COVID-19

The risk for hospitalization and disease progression among nursing home residents with COVID-19 infection was reduced following receipt of either molnupiravir or nirmatrelvir-ritonavir.

Oral antiviral therapy with either molnupiravir or nirmatrelvir-ritonavir reduced the risk for hospitalization and disease progression among patients with COVID-19 residing in nursing homes, according to study results published in JAMA Network Open.

Researchers conducted a territory-wide retrospective cohort study in Hong Kong from February through March of 2022. Eligible patients were nursing home residents with COVID-19 infection confirmed via polymerase chain reaction testing. Patients at high risk for deterioration were prescribed either molnupiravir or nirmatrelvir/ritonavir within 5 days of symptom onset. Exclusion criteria included hospitalization on the first day of consultation and use of both oral antiviral treatments. 

The primary endpoint was time to initial hospitalization. The secondary endpoint was a composite outcome of inpatient disease progression, defined as intensive care unit admission, receipt of invasive mechanical ventilation, and mortality. Propensity scores were calculated for all patients and estimated via multinomial logistic regression, with adjustments for clinical and demographic characteristics. Use of molnupiravir o nirmatrelvir-ritonavir was modeled as a time-dependent covariate in a weighted Cox model. 

A total of 14,617 patients were included in the final analysis, of whom the mean (SD) age was 84.8 (10.2) years, and 56.2% were women. In total, 8939 (61.2%) patients did not use oral antivirals, 5195 (35.5%) were prescribed molnupiravir, and 483 (3.3%) were prescribed nirmatrelvir-ritonavir. Patients who were vs were not prescribed oral antiviral therapy were more likely to be women, have fewer comorbidities, and have lower hospitalization rates. 

[H]ealth authorities should allocate adequate resources for timely use of antiviral treatments for nursing home patients…

After a median follow-up period of 30 (IQR, 30-30) days, 6223 (42.6%) patients were hospitalized. Of the hospitalized population, 59.6% were nonusers of oral antivirals, whereas 16% used molnupiravir and 12.4% used nirmatrelvir-ritonavir.

Inpatient disease progression occurred in 2307 patients, of whom 23.5% were nonusers of oral antivirals, 3.8% were prescribed molnupiravir, and 1.0% were prescribed nirmatrelvir-ritonavir. 

After balancing baseline clinical characteristics via propensity score weighting, the researchers found that oral antiviral use was associated with decreased risk for hospitalization. Both molnupiravir use (weighted hazard ratio [wHR], 0.46; 95% CI, 0.35-0.57; P <.001) and nirmatrelvir-ritonavir use (wHR, 0.46; 95% CI, 0.32-0.65; P <.001) were associated with decreased hospitalization risk.

The risk for inpatient disease progression was also found to decrease following receipt of molnupiravir (wHR, 0.35; 95% CI, 0.23-0.51; P <.001) or nirmatelvir-ritonavir (wHR, 0.13; 95% CI, 0.06-0.44; P <.001).

In multivariable analyses, similar outcomes were observed when molnupiravir and nirtmatelvir/ritonavir recipients were compared with those who did not use oral antiviral therapy. 

Limitations of this study include potential ascertainment bias, missing laboratory data, and the relatively low rate of COVID-19 vaccination among the population. Further, hospital overcrowding due to the COVID-19 pandemic may have led to lower hospitalization rates. 

According to the researchers “[H]ealth authorities should allocate adequate resources for timely use of antiviral treatments for nursing home patients…”

Disclosures: Multiple study authors declared affiliations with pharmaceutical, biotech, and/or device companies. Please see the reference for a full list of authors’ disclosures.

This article originally appeared on Infectious Disease Advisor


Ma BH, Yip TC, Lui GC, et al. Clinical outcomes following treatment for COVID-19 with nirmatrelvir/ritonavir and molnupiravir among patients living in nursing homes.  JAMA Netw Open. Published online April 27, 2023. doi:10.1001/jamanetworkopen.2023.10887