Infection with Tecovirimat-Resistant Mpox Virus Is on the Rise in the U.S.

Clusters of infection with a tecovirimat-resistant mpox variant have recently occurred in five states, mostly among persons who had not received tecovirimat.

Tecovirimat, a drug approved for treatment of smallpox based on animal studies, is being evaluated for efficacy in treating infection with mpox virus (MPXV) and has been used widely in the U.S. since the worldwide mpox outbreak was recognized in 2022.

Between 2023 and 2024, specimens from 18 patients in 5 states have yielded tecovirimat-resistant MPXV. Four patients had traveled to states in which this resistance mutation was recognized. None of the 18 had previously received tecovirimat. Isolates contained mutations in an MPXV gene that has been associated with resistance to the drug.

Comment

It's no surprise when drug res…

Reviewing Author

Stephen G. Baum, MD

Disclosures

Consultant/Advisory BoardClinical Infectious Diseases

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