First Smallpox Medication Approved by FDA

The U.S. Food and Drug Administration (FDA) today approved TPOXX (tecovirimat), the first drug with an indication for treatment of smallpox.

Smallpox is a serious, highly contagious, and sometimes fatal infectious disease. Complications of smallpox include encephalitis (inflammation of the brain), corneal ulcerations (an open sore on the clear, front surface of the eye) and blindness.

Though the World Health Organization (WHO) declared smallpox, eradicated in 1980, there have been long-standing concerns that smallpox could be used as a bioweapon.

This FDA approval is important since there is no proven treatment for smallpox disease. Variola virus, the virus that causes smallpox, was mainly spread by direct contact between people.

Additionally, smallpox can be prevented by the smallpox vaccine. Currently, there is one licensed smallpox vaccine; ACAM2000, licensed on August 31, 2007, which is manufactured by Sanofi Pasteur Biologics Co.

If you get the vaccine:

• Before contact with the virus, the vaccine can protect you from getting sick.
• Within 3 days of being exposed to the virus, the vaccine might protect you from getting the disease. If you still get the disease, you might get much less sick than an unvaccinated person would.
• Within 4 to 7 days of being exposed to the virus, the vaccine likely gives you some protection from the disease. If you still get the disease, you might not get as sick as an unvaccinated person would.

During February 2018, a biotechnology company announced positive results from a Phase 3 pivotal study of its investigational, non-replicating smallpox vaccine, IMVAMUNE.

TPOXX’s effectiveness against smallpox was established by studies conducted in animals infected with viruses that are closely related to the virus that causes smallpox and was based on measuring survival at the end of the studies.

TPOXX was approved under the FDA’s Animal Rule, which allows efficacy findings from adequate and well-controlled animal studies to support an FDA approval when it is not feasible or ethical to conduct efficacy trials in humans.

The safety of TPOXX was evaluated in 359 healthy human volunteers without a smallpox infection.

“This new treatment affords us an additional option should smallpox ever be used as a bioweapon,” said FDA Commissioner Scott Gottlieb, M.D.

"This is the first product to be awarded a Material Threat Medical Countermeasure priority review voucher. Today’s action reflects the FDA’s commitment to ensuring that the U.S. is prepared for any public health emergency with timely, safe and effective medical products.”

The FDA granted this application Fast Track and Priority Review designations. TPOXX also received Orphan Drug designation, which provides incentives to assist and encourage the development of drugs for rare diseases and a Material Threat Medical Countermeasure Priority Review Voucher, which provides additional incentives for certain medical products intended to treat or prevent harm from specific chemical, biological, radiological and nuclear threats.

TPOXX was developed in conjunction with the U.S. Department of Health and Human Services’ Biomedical Advanced Research and Development Authority (BARDA).

FDA, an agency within the U.S. Department of Health and Human Services, protects the public health by assuring the safety, effectiveness, and security of human and veterinary drugs, vaccines and other biological products for human use, and medical devices.