Oral Nirmatrelvir-Ritonavir for Covid-19 in Higher-Risk Outpatients
Clinical Snapshot
PICO Framework
| P — Population | Higher-risk adults (≥50 years or ≥18 years with comorbidities) with SARS-CoV-2 infection, predominantly vaccinated, unwell ≤5 days |
| I — Intervention | Nirmatrelvir 300mg-ritonavir 100mg twice daily for 5 days plus usual care |
| C — Comparator | Usual care alone |
| O — Outcomes | Primary: hospitalization or death from any cause within 28 days. Secondary: viral load reduction, adverse events |
Bottom Line
This large platform trial of over 4,000 higher-risk adults provides compelling evidence that nirmatrelvir-ritonavir does not reduce hospitalization or death in vaccinated COVID-19 patients. With very low baseline event rates (0.6-1.2%) and confidence intervals crossing unity, the study demonstrates no clinically meaningful benefit in this population. The open-label design introduces bias risk, but the large sample size and real-world setting enhance generalizability. For Australian clinicians, these findings question the routine use of nirmatrelvir-ritonavir in vaccinated higher-risk patients, particularly given potential drug interactions, cost considerations, and the 13 serious adverse events reported. The results suggest that the original benefit demonstrated in unvaccinated populations may not translate to the current predominantly vaccinated cohort, supporting a more selective prescribing approach focused on the highest-risk unvaccinated individuals.
Key Findings
P Value: Probability of superiority: PANORAMIC 0.334, CanTreatCOVID 0.830
Effect Size: PANORAMIC adjusted OR 1.18, CanTreatCOVID adjusted OR 0.48
Primary Outcome: Hospitalization or death within 28 days: PANORAMIC 0.8% vs 0.7%, CanTreatCOVID 0.6% vs 1.2%
Nnt Or Sensitivity: No meaningful NNT calculable due to lack of significant benefit
Confidence Interval: PANORAMIC 95% BCI 0.55-2.62, CanTreatCOVID 95% BCI 0.08-2.23
Clinical Application
Readily available through PBS but requires consideration of drug interactions and contraindications Results challenge current PBS listing for nirmatrelvir-ritonavir in vaccinated populations; may inform RACGP guideline updates and TGA benefit-risk assessment Higher-risk vaccinated adults with COVID-19 in community settings, particularly those ≥50 years or with comorbidities
Abstract
BACKGROUND: Nirmatrelvir-ritonavir has been shown to reduce progression to severe illness from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in unvaccinated high-risk outpatients. The effectiveness of nirmatrelvir-ritonavir in persons who have been vaccinated, infected naturally, or both is unclear. METHODS: In two open-label platform trials (PANORAMIC in the United Kingdom and CanTreatCOVID in Canada), we enrolled higher-risk adults (≥50 years of age or ≥18 years of age with coexisting conditions) in the community who tested positive for SARS-CoV-2 and had been unwell for 5 days or less. The participants were randomly assigned to receive usual care plus nirmatrelvir (300 mg)-ritonavir (100 mg) twice a day for 5 days or to receive usual care alone. The primary outcome was hospitalization or death from any cause within 28 days after randomization. RESULTS: From December 8, 2021, to September 30, 2024, a total of 3516 participants in the PANORAMIC trial and 716 participants in the CanTreatCOVID trial underwent randomization. In the PANORAMIC trial, 14 of 1698 participants (0.8%) in the nirmatrelvir-ritonavir group and 11 of 1673 participants (0.7%) in the usual-care group were hospitalized or died (adjusted odds ratio, 1.18; 95% Bayesian credible interval, 0.55 to 2.62; probability of superiority, 0.334). In the CanTreatCOVID trial, 2 of 343 participants (0.6%) in the nirmatrelvir-ritonavir group and 4 of 324 participants (1.2%) in the usual-care group were hospitalized or died (adjusted odds ratio, 0.48; 95% Bayesian credible interval, 0.08 to 2.23; probability of superiority, 0.830). In a substudy involving 634 participants, viral load was reduced by the end of treatment with nirmatrelvir-ritonavir. Serious adverse events with nirmatrelvir-ritonavir were reported in 9 participants in the PANORAMIC trial and in 4 participants in the CanTreatCOVID trial. CONCLUSIONS: In two open-label trials, nirmatrelvir-ritonavir did not reduce the incidence of hospitalization or death among vaccinated higher-risk participants with SARS-CoV-2 infection. (Funded by the National Institute for Health and Care Research, and others; PANORAMIC ISRCTN number, 2021-005748-31; CanTreatCOVID ClinicalTrials.gov number, NCT05614349.).
References
- 1.Butler, C. C., Pinto, A. D., Harris, V., Holmes, J., Rahman, N. M., Cureton, L., Hayward, G., Richards, D. B., Lowe, D. M., Standing, J. F., Breuer, J., Hood, K., Png, M. E., Petrou, S., Dorward, J., Patel, M. G., Thomas, N. P. B., Evans, P., Hart, N. D., Jani, B. D., Hosseini, B., Murthy, S., McBrien, K., Condon, A., McDonald, E. G., Daley, P., Greiver, M., da Costa, B. R., Selby, P., Jüni, P., Lee, T. C., Shi, H., Detry, M. A., Saunders, C. T., Fitzgerald, M., Berry, N. S., Saville, B. R., Khoo, S. H., Nguyen-Van-Tam, J. S., Hobbs, F. D. R., Yu, L. M., & Little, P. (2026). Oral nirmatrelvir-ritonavir for Covid-19 in higher-risk outpatients. *New England Journal of Medicine*. https://doi.org/10.1056/NEJMoa2502457
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