A recent clinical trial in the Democratic Republic of the Congo (DRC) has revealed that tecovirimat, a promising antiviral drug, failed to improve symptoms in patients infected with mpox. The study, conducted in the epicenter of the ongoing outbreak, found that tecovirimat did not significantly reduce the characteristic blister-like rash associated with the disease. This outcome is particularly concerning as mpox continues to spread in Central Africa, highlighting the urgent need for effective treatments.
The trial, sponsored by the US National Institute of Allergy and Infectious Diseases (NIAID), involved nearly 600 participants who were randomly assigned to receive either tecovirimat or a placebo. All participants received supportive care, including nutrition, hydration, and treatment for secondary infections, and were closely monitored in a hospital setting for at least 14 days. While tecovirimat was found to be safe, it did not demonstrate a significant improvement in lesion clearance compared to the placebo.
Lori Dodd, branch chief of NIAID’s clinical trials research and statistics branch, stated that the agency shared the initial results ahead of peer review “due to the urgent need for scientific evidence on the use of tecovirimat for the treatment of mpox.” This urgency was further underscored by the World Health Organization's (WHO) declaration of the mpox outbreak in Central Africa as a global health emergency on August 14.
Impact on Mpox Treatment Landscape
Tecovirimat was approved by the US Food and Drug Administration (FDA) in 2018 for the treatment of smallpox, a related virus. Amid the global mpox outbreak in 2022, trials were initiated to assess its efficacy against mpox. The drug has also been available in the US through an expanded access program, and it was approved for mpox in the UK and Europe under exceptional circumstances, even without comprehensive efficacy data. The failure of tecovirimat in this trial raises questions about its widespread use for mpox, especially in resource-limited settings.
Unexpectedly Low Mortality Rate
Interestingly, the study revealed a lower-than-expected mortality rate among participants, regardless of whether they received tecovirimat or the placebo. The overall mortality rate was 1.7 percent, significantly lower than the 3.6 percent or higher reported among all mpox cases in the DRC. Additionally, patients' lesions cleared up faster than anticipated in both groups, suggesting that supportive care may play a more significant role in managing the disease than previously thought.
WHO Strategic Plan
In response to the ongoing outbreak, the WHO launched a six-month strategic plan aimed at controlling the spread of mpox in the DRC and neighboring countries. The plan, estimated to cost $135 million, focuses on enhancing surveillance efforts and improving access to testing and vaccines. Tedros Adhanom Ghebreyesus, WHO Director-General, emphasized that “the mpox outbreaks in the Democratic Republic of the Congo and neighboring countries can be controlled, and can be stopped.”
