FRIDAY, Sept. 16, 2022 (HealthDay News) -- U.S. health officials are advising doctors not to overuse the only antiviral for monkeypox because there is a risk of the virus mutating and rendering the drug useless.
TPOXX (tecovirimat) works by targeting just one protein found on monkeypox, as well as smallpox and similar viruses. Its use for monkeypox is still considered experimental, according to the U.S. Food and Drug Administration.
Even a single molecular change to the virus "could have a large impact on the antiviral activity of TPOXX," the FDA said in an online update.
"For most patients with intact immune systems, supportive care and pain control may be enough," the U.S. Centers for Disease Control and Prevention said in a statement.
Though TPOXX has been prescribed to tens of thousands of patients so far and public health officials have sent 37,000 courses of the drug to physicians, the CDC is still asking doctors to submit an application to prescribe the medication. Doctors must document patient need and agree to track results and side effects, CBS News reported.
Meanwhile, the U.S. National Institutes of Health will conduct a study with more than 500 patients in 60 locations to track for any signs of mutations in the monkeypox virus.
Resistance is always a risk with antiviral drugs, said Dr. Anthony Fauci, the nation's leading infectious diseases expert.
"That's why we’re uncomfortable when you only have a single drug," Fauci said during Thursday media briefing on monkeypox.
Research in labs, animals and people have suggested that monkeypox could develop resistance to the antiviral in multiple ways, the FDA said.
The decision to restrict antiviral use runs counter to requests by HIV advocates and other patient groups who have pressed for making the antiviral more available in recent weeks.
It also comes as federal officials are showing cautious optimism about the outbreak. Cases have fallen 50% after a peak last month, according to the CDC.
CDC Director Dr. Rochelle Walensky said during the Thursday monkeypox briefing that vaccinations, educational outreach and reduction in behaviors linked to spread have had an impact.
The Biden administration invoked emergency powers last month to stretch the vaccine supply, and also expedited the use of experimental monkeypox tests this month.
The World Health Organization has more on monkeypox.
SOURCE: Associated Press