MPOX TRACKER

A concerning development in the fight against mpox has emerged as U.S. health officials report a cluster of cases resistant to the antiviral drug tecovirimat (TPOXX) across five states. The Centers for Disease Control and Prevention (CDC) identified 18 individuals infected with clade II mpox between October 6, 2023, and February 15, 2024, who had never previously received TPOXX treatment.

This multi-state outbreak follows an earlier, unrelated cluster of drug-resistant cases in California in late 2022 to early 2023. Health officials caution that the true extent of drug-resistant cases may be underestimated, as not all mpox infections undergo genetic sequencing to determine the specific variant.

The clade II strain, endemic to West Africa, was responsible for the global outbreak in 2022 that led the World Health Organization to declare a public health emergency. While cases have declined, the virus continues to spread at low levels in some countries.

In response to these findings, the CDC advises healthcare providers to closely adhere to TPOXX treatment protocols, ensure proper patient compliance, and emphasize that patients can still transmit the virus while undergoing treatment. The emergence of drug resistance underscores the urgent need for additional mpox treatments and heightened surveillance efforts.

It's important to note that this clade II strain is distinct from the ongoing outbreak in Africa of a new variant called clade Ib, which prompted another WHO public health emergency declaration in August. A recent U.S. government-backed study found that TPOXX was not effective in accelerating recovery from clade Ib infections compared to a placebo.

Mpox, characterized by flu-like symptoms and pus-filled lesions, is typically mild but can be fatal in immunocompromised individuals. As a disease transmitted through close physical contact, including sexual activity, the emergence of drug-resistant strains poses significant challenges for public health efforts to contain its spread.