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Oral Nirmatrelvir-Ritonavir as Postexposure Prophylaxis for Covid-19
Jennifer Hammond1, Carla Yunis1, Robert J Fountaine1
1From Global Product Development, Pfizer, Collegeville, PA (J.H.); Global Product Development, Pfizer, Lake Mary (C.Y.), and Global Product Development, Pfizer, Tampa (J.M.R.) - both in Florida; Global Product Development, Pfizer, Groton, CT (R.J.F., H.S.); Global Product Development, Pfizer International Organization, Paris (G.L.); Pfizer, Chicago (A.M.B.); Global Product Development, Pfizer, Lake Forest, IL (W.Z., W.W.); Early Clinical Development, Pfizer, Cambridge, MA (M.L.B.); Medical and Safety, Pfizer Research and Development UK, Sandwich, United Kingdom (V.M.H.); Specialized Hospital for Active Treatment of Pneumo-Phthisiatric Diseases, Haskovo, Bulgaria (V.K.); and Global Product Development, Pfizer, New York (R.P.).
Nirmatrelvir-ritonavir did not significantly reduce the risk of symptomatic coronavirus disease 2019 (Covid-19) infection in a postexposure prophylaxis trial. This study found no significant benefit for either 5-day or 10-day treatment regimens compared to placebo.
Area of Science:
- Infectious Diseases
- Virology
- Clinical Pharmacology
Background:
- Previous clinical trials have not established a significant benefit for postexposure prophylaxis in preventing coronavirus disease 2019 (Covid-19).
- Investigating novel therapeutic strategies is crucial for managing SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) transmission and infection.
Purpose of the Study:
- To evaluate the efficacy and safety of nirmatrelvir-ritonavir as a postexposure prophylaxis for Covid-19.
- To determine if a 5-day or 10-day regimen of nirmatrelvir-ritonavir can prevent symptomatic SARS-CoV-2 infection in individuals exposed to the virus.
Main Methods:
- A phase 2-3, double-blind, placebo-controlled trial was conducted.
- Participants were asymptomatic, SARS-CoV-2 negative adults exposed to Covid-19 within 96 hours.
- Random assignment to receive nirmatrelvir-ritonavir (300 mg/100 mg) every 12 hours for 5 days, 10 days, or placebo.
Main Results:
- Symptomatic SARS-CoV-2 infection developed in 2.6% (5-day group), 2.4% (10-day group), and 3.9% (placebo group) by day 14.
- No statistically significant reduction in symptomatic infection was observed for either nirmatrelvir-ritonavir regimen compared to placebo.
- Adverse events were similar across groups, with dysgeusia being the most common side effect.
Conclusions:
- Postexposure prophylaxis with nirmatrelvir-ritonavir for 5 or 10 days did not significantly decrease the risk of developing symptomatic SARS-CoV-2 infection.
- The findings suggest that nirmatrelvir-ritonavir is not effective as a preventive measure against Covid-19 in this specific postexposure setting.
- Further research may be needed to explore other prophylactic strategies or treatment indications for nirmatrelvir-ritonavir.
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