By IDSE News Staff
The antiviral tecovirimat (TPOXX, SIGA Technologies) appears to be safe and effective for the treatment of monkeypox virus (MPV) symptoms and skin lesions, according to a University of California Davis Health study.
Tecovirimat is an FDA-approved antiviral drug for the treatment of smallpox. It limits viral spread in the body by inhibiting the work of the protein involved in the release of the enveloped virus. Recently, the CDC allowed physicians to prescribe tecovirimat on a compassionate-use basis to treat adults and children with orthopoxvirus infections, including MPV.
The recent global outbreak of monkeypox has led to more than 45,500 cases as of Aug. 22, 2022. While symptoms usually resolve on their own in two to four weeks, a recent study showed that 13% of patients required hospitalization.
The new study included patients referred to UC Davis Medical Center, primarily through the Sacramento County Department of Public Health, between June 3 and Aug. 13 (JAMA 2022 Aug 22. doi:10.1001/jama.2022.15336).
Patients with skin lesions on multiple body parts or in sensitive areas, such as the face or genital region, were offered oral tecovirimat treatment. The treatment was weight-based, given every eight or 12 hours, and was taken within 30 minutes of a high-fat meal.
The researchers collected clinical data at the first in-person evaluation for treatment and by in-person or telephone interview on days 7 and 21 following the beginning of therapy.
In total, 25 patients with confirmed MPV infection completed a course of tecovirimat therapy. All were male. Their ages ranged between 27 and 76 years (median age, 40 years). Nine patients had HIV.
Only one patient had the smallpox vaccine (taken more than 25 years ago) and four others received a dose of Jynneos (Bavarian Nordic) vaccination after symptoms started.
The study found that 92% of patients had lesions in their genital or anal area. While all patients had painful lesions, around half had fewer than 10 lesions over their entire bodies.
On average, patients had symptoms or lesions for 12 days before they started their antiviral treatment. Fever was the most common symptom (76% of the patients), followed by fatigue (32%), sore throat (20%) and chills (20%). Other symptoms included backache (12%), muscle pain (8%), nausea (4%) and diarrhea (4%).
All patients completed the tecovirimat therapy and tolerated their treatment well. They were treated for two weeks, except for one patient who was treated for 21 days.
On day 7 of therapy, 40% of patients had healed from their lesions. By day 21, 92% had healed and were pain-free.
The most reported adverse events on day 7 of therapy included fatigue (28%), headache (20%), nausea (16%), itching (8%) and diarrhea (8%).
“We have to be very careful in how we interpret the data. It is hard to differentiate the side effects due to therapy from those caused by the infection,” said infectious diseases expert and co-author George Thompson, MD, a professor in the Department of Internal Medicine, Division of Infectious Diseases, and the Department of Medical Microbiology and Immunology at the UC Davis School of Medicine, in Sacramento.
“We have very limited clinical data on the use of tecovirimat for monkeypox infection. There is much to learn about the natural progression of the disease and how tecovirimat and other antivirals may affect it,” said lead author Angel Desai, MD, an adult infectious disease specialist at UC Davis Health.
The study was small and did not include a control group. So, assessing antiviral efficacy in terms of symptom duration and severity was limited. Also, the time from symptom onset to starting the antiviral therapy varied among the patients.
