NEJM: Volume 394, Issue 9 – February 26, 2026 Research

March 1, 2026 Ananya Mittal - World Editor

The landscape of mpox treatment received a significant update this month with findings published in the Novel England Journal of Medicine. A study, detailed in the February 26, 2026 issue (Volume 394, Issue 9, pages 884-895), offers further insight into the efficacy of tecovirimat – also known as TPOXX – for managing the infection. This development arrives as global health authorities continue to monitor mpox activity and refine strategies for prevention and care.

Tecovirimat: How it Works and Initial Approvals

Tecovirimat is an antiviral medication originally developed to combat smallpox. Because mpox and smallpox are caused by viruses in the same family (orthopoxviruses), tecovirimat was authorized for use against mpox under emergency use authorizations in several countries, including the United States, during the 2022-2023 outbreak. The drug works by inhibiting the VP37 protein of the virus, which is crucial for viral spread. Essentially, it prevents the virus from escaping infected cells to infect others.

The New England Journal of Medicine Study: A Closer Look

The study published in NEJM builds on earlier observations of tecovirimat’s potential. While the full details of the study design are available in the journal, it involved a retrospective analysis of data from patients treated with tecovirimat. Researchers assessed clinical outcomes, including lesion counts, time to crusting (when lesions dry and are no longer contagious) and the duration of viral shedding. The study aimed to provide more robust evidence regarding the drug’s effectiveness in a real-world setting.

It’s important to note that retrospective studies, like this one, have inherent limitations. They rely on existing data, which may not be complete or consistently collected. This can introduce bias and make it demanding to establish definitive cause-and-effect relationships. The researchers acknowledge these limitations, emphasizing that further prospective, randomized controlled trials are needed to confirm these findings.

Who is Affected by Mpox and Current Transmission Patterns

Mpox, formerly known as monkeypox, is a viral infection that can cause a rash, fever, headache, muscle aches, and swollen lymph nodes. While historically concentrated in parts of Central and West Africa, the 2022-2023 outbreak saw a significant increase in cases globally, particularly among men who have sex with men. However, it’s crucial to understand that anyone can contract mpox through close contact with an infected person or contaminated materials. The Centers for Disease Control and Prevention (CDC) provides detailed information on transmission and risk factors.

As of early 2026, mpox cases have declined significantly from the peak of the outbreak, but sporadic cases continue to be reported. Ongoing surveillance is essential to monitor for potential resurgences and identify any changes in transmission patterns. The World Health Organization (WHO) continues to provide global updates and guidance on mpox.

Interpreting the Evidence: What Does the Study Suggest?

The NEJM study suggests that tecovirimat may be associated with improved clinical outcomes in patients with mpox. Specifically, the research indicated a potential reduction in the duration of viral shedding and a faster time to lesion crusting among those treated with the drug. However, the researchers caution that these findings are preliminary and require confirmation through more rigorous studies. It’s also important to remember that correlation does not equal causation. While the study observed an association between tecovirimat use and improved outcomes, it cannot definitively prove that the drug *caused* those improvements.

The study also highlighted the importance of early treatment. Patients who received tecovirimat earlier in the course of their illness appeared to experience greater benefits. This underscores the need for prompt diagnosis and access to treatment for individuals suspected of having mpox.

Public Health Implications and Guidance Updates

The findings from the NEJM study are likely to inform ongoing discussions among public health officials regarding the optimal use of tecovirimat. Current guidance from health authorities generally recommends considering tecovirimat for individuals with severe mpox or those at high risk of complications. However, the specific criteria for treatment may vary depending on local circumstances and available resources.

The European Centre for Disease Prevention and Control (ECDC) regularly updates its risk assessments and guidance on mpox based on the latest scientific evidence. It’s essential for healthcare professionals and the public to stay informed about these updates.

What Comes Next: Ongoing Research and Surveillance

Several key areas of research are currently underway to further refine our understanding of mpox and improve treatment strategies. These include:

  • Prospective Clinical Trials: Randomized controlled trials are needed to definitively assess the efficacy of tecovirimat and other potential treatments.
  • Vaccine Effectiveness Studies: Research is ongoing to evaluate the long-term effectiveness of the JYNNEOS vaccine against mpox.
  • Surveillance and Genomic Sequencing: Continued surveillance is crucial to monitor for new variants of the virus and track transmission patterns. Genomic sequencing can help identify the origins of outbreaks and inform public health interventions.

The ongoing investigations into primary measles infection, as detailed in a separate recent publication in the New England Journal of Medicine (February 26, 2026), highlight the broader importance of continued research into infectious diseases and the need for a proactive approach to public health preparedness. Understanding the dynamics of viral infections, like mpox and measles, is essential for protecting communities and preventing future outbreaks.