New Mpox Lesions After Tecovirimat Treatment, New York City, 2022

Monkeypox virus, which causes mpox, can cause serious illness through skin and mucosal lesions. During the 2022 multinational outbreak, tecovirimat, an antiviral approved for smallpox, was used as an investigational treatment for severe mpox, though its effectiveness and the best length of treatment were still being studied. An earlier assessment had found three patients who developed new lesions after finishing treatment. This report describes a series of such patients in New York City.

The cases

A case was a New York City resident with probable or confirmed mpox who developed new skin or mucosal lesions within 30 days of finishing the recommended 14-day course of tecovirimat, after the first lesions had improved or cleared. In August and September 2022, providers reported 10 such cases to the city health department, and surveys were returned for nine.

• Patients: median age 33 (range 23 to 46); eight men and one transgender woman. Four were Black and four White among those whose race was reported, and two were Hispanic or Latino.
• HIV: five had HIV. Four were taking antiretrovirals, with CD4 counts above 350 cells/mm³ and viral loads under 200 copies/mL; one was not, with a CD4 count below 200.
• Vaccination: none had received the JYNNEOS vaccine before getting mpox.
• First illness: all initial lesions tested positive for orthopoxvirus. The median severity score was 8 out of 23. Of six patients tested for other sexually transmitted infections, one had gonorrhea and was treated.

Treatment and what followed

Patients started tecovirimat a median of 9 days after symptoms began. All took weight-appropriate oral doses as outpatients, completed the 14 days with full adherence, reported no side effects, and had improving lesions at the end.

New lesions appeared a median of 13 days after treatment ended (range 2 to 30 days). In eight patients they were milder than the originals (median severity score 3). Of six patients whose new lesions were tested for orthopoxvirus, one was positive, and of two retested for sexually transmitted infections, one had syphilis — both results in the patient with untreated HIV. Two patients restarted tecovirimat, for 7 and 14 more days, and their lesions cleared. Of the seven who did not, six saw their lesions clear and one was lost to follow-up.

What it means

The cause of these new lesions is unknown. Monkeypox virus might recur, as other viruses such as SARS-CoV-2 can, at levels too low for tests to detect. Because most new lesions in this series cleared without more treatment, people with healthy immune systems may not need another course of tecovirimat, but the course may be more complicated in immunocompromised patients. Gaps in testing for sexually transmitted infections, both at diagnosis and when new lesions appeared, were missed chances to find coinfections or other diagnoses.

Limitations

• Cases were reported voluntarily, so the true number is likely higher.
• Not all new lesions were tested for orthopoxvirus or other causes.
• The findings rely on providers' reports, which can be subjective.

Sources

• Leah Seifu, Elizabeth Garcia, Tristan D. McPherson, Maura Lash, Karen A. Alroy, Mary Foote, Ellen H. Lee, Jeffrey Kwong, Asa Radix, Paul Riska, Jason Zucker, Sarah Zuercher and Marcia Wong, "Notes from the Field: Posttreatment Lesions After Tecovirimat Treatment for Mpox — New York City, August–September 2022," Morbidity and Mortality Weekly Report, CDC: https://www.cdc.gov/mmwr/volumes/72/wr/mm7217a5.htm