Smallpox Drug Will Be Stockpiled by U.S Government in Case of Bioterrorism Attack

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The smallpox virus is shown here in this photo. The U.S. Food and Drug Administration approved the first drug to treat smallpox, which could stop a pandemic were the virus to be released as a weapon of bioterrorism. BSIP/UIG via Getty Images

The deadly smallpox virus has long been eradicated around the world, but experts fear the virus could be turned into a biological weapon. To combat this potential threat, the U.S. Food and Drug Administration approved the first drug to treat smallpox last Friday.

Siga Technologies, now based in New York, has already delivered 2 million treatments of the antiviral pill called Tpoxx, or tecovirimat, which the government will stockpile in case of a terror attack.

"This new treatment affords us an additional option should smallpox ever be used as a bioweapon," Dr. Scott Gottlieb, the FDA's commissioner, said in a statement.

A 19th-century painting shows a doctor vaccinating babies with cowpox to protect them against the more virulent smallpox. The U.S. Food and Drug Administration has approved the first drug to treat smallpox. Arterra/UIG via Getty Images

People in the United States are no longer routinely vaccinated against this contagious and deadly virus—a global vaccination campaign led to its eradication in 1980, but most people younger than 40 are not protected. Smallpox kills about 30 percent of all unvaccinated individuals, according to the Centers for Disease Control and Prevention.

Even after the virus was wiped out, a few small samples were left behind for scientific study. For years, the World Health Organization has debated whether to destroy the last remaining known samples of the virus, one in the U.S. and another in Russia. NPR previously reported that both countries had resisted calls to destroy their smallpox samples, explaining they were needed for research.

The new drug could offer protection against a deadly outbreak should the virus fall into the wrong hands.

Tpoxx has been tested on monkeys and rabbits, which were infected with a virus similar to smallpox. More than 90 percent survived, according to the company.

Tpoxx was also tested on hundreds of healthy human volunteers without a smallpox infection. The side effects most often reported included headaches, nausea and abdominal discomfort.

Smallpox killed about 300 million people during the 20th century before the World Health Organization's worldwide eradication efforts began in 1967. The virus is spread mostly through direct contact, according to the FDA. The virus would typically hide in the body for up to 14 days before a person displayed any symptoms, which initially include fever, accompanied by a headache and backache. The rash for which smallpox gets its name consists of small, pink bumps that progress into pus-filled sores that erupt throughout the body and often leave scars.

More severe complications can include inflammation of the brain and sores in the eyes that can lead to blindness.

"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," Gottlieb said.