There is no proven treatment for smallpox disease in people sick with smallpox. There are three antiviral therapies that have shown effectiveness against poxviruses in animals and in vitro studies; however, their effectiveness in treating smallpox disease in humans is unknown.
In July 2018, the U.S. Food and Drug Administration (FDA) approved tecovirimat (TPOXX), the first drug with an indication for treatment of smallpox. Tecovirimat’s effectiveness against smallpox was established in vitro against variola virus, the causative agent of smallpox. Efficacy of tecovirimat treatment has also been demonstrated within multiple animal model studies measuring survival in animals infected with either variola virus or other closely related Orthopoxviruses. Furthermore, treatment with tecovirimat minimized signs of morbidity as well as protected from mortality within prairie dogs challenged with monkeypox virus. The safety of tecovirimat was evaluated in 359 healthy human volunteers. Tecovirimat 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 FDA Antimicrobial Drugs Advisory Committee voted unanimously (17 to 0) that the benefits of tecovirimat outweigh its risks.
Treatment of smallpox patients generally involves supportive care. Vaccination can prevent or lessen the severity of disease if given within 2 to 3 days of the initial exposure. It may decrease symptoms if given within the first week of exposure.
Emergency Use of Smallpox Medical Countermeasures
During a declared public health emergency involving smallpox, CDC will provide more detailed guidance regarding the availability and use of smallpox medical countermeasures from the Strategic National Stockpile under their appropriate regulatory mechanism (IND, EUA, or Emergency Use Instructions [EUI]).