Effectiveness of Tecovirimat in Mpox Cases: A Systematic Review of Current Evidence

Mpox, formerly known as monkeypox, has re-emerged as a significant global health concern, particularly during the widespread outbreak of 2022. As an orthopoxvirus related to the eradicated smallpox virus, mpox has been primarily managed with smallpox vaccines and treatments, including the antiviral agent Tecovirimat. This systematic review aims to evaluate the effectiveness and safety of Tecovirimat in treating mpox, focusing on its use during the 2022 outbreak, especially among high-risk populations, including men who have sex with men and people living with HIV. We conducted a comprehensive search across databases, such as Embase, PubMed, and Web of Science, up to August 30, 2024. The selection involved a two-stage review process utilizing the Nested Knowledge platform, which helped streamline the screening and data extraction. We included studies that focused on the clinical efficacy and safety of Tecovirimat in human patients with confirmed mpox infections. Our analysis mainly synthesized data narratively due to the heterogeneity of study designs and outcomes. Fifteen studies met the inclusion criteria, providing data on 1031 mpox cases. The preliminary analysis of the PALM 007 RCT indicated that tecovirimat did not significantly outperform placebo in lesion resolution for all patients. Lesions healed faster than expected, regardless of tecovirimat or placebo treatment. A lower mortality rate of 1.7% among those enrolled in the PALM 007 RCT was observed, compared to the general mpox mortality rate of 3.6% or higher in the DRC. Observational studies revealed that early administration of Tecovirimat, especially within the first week of symptom onset, significantly improves symptom resolution, reduces the severity of the disease, and decreases the likelihood of hospitalization and complications in observational studies. However, the impact on viral clearance was inconsistent, and some studies suggested limited efficacy in severely immunocompromised patients. Regarding safety, Tecovirimat was generally well-tolerated as indicated by the RCT; however, mild adverse effects such as fatigue, headache, and nausea were commonly reported among observational studies. Serious adverse events were rare but included elevated liver enzymes and psychiatric symptoms, particularly in patients with pre-existing conditions. Tecovirimat demonstrates some potential benefits in treating mpox, particularly when administered early. The PALM 007 RCT failed to meet the efficacy point. Tecovirimat is generally well-tolerated with a favorable safety profile, although monitoring is advisable for those with existing liver or renal conditions. Despite promising results, further large-scale randomized controlled trials are needed to fully ascertain the drug's effectiveness across diverse populations and to explore its impact on viral clearance and transmission dynamics.