Thanks in part to Army scientists, the world has gained a new weapon in the fight against one of history's most feared diseases: smallpox.A new vaccine approved on Sept. 24 by the U.S. Food and Drug Administration (FDA), prevents both smallpox and the related disease monkeypox in adults. Marketed under the brand name JYNNEOS, the vaccine was developed by biotechnology firm Bavarian Nordic and tested by the U.S. Army Medical Research and Development Command's (USAMRDC) U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID)."In addition to its public health importance, this vaccine will have a direct impact on improving force health protection for U.S. troops who are required to be immunized against smallpox," said Col. E. Darrin Cox, Commander of USAMRIID; which is headquartered at Fort Detrick, Maryland.Following a worldwide smallpox vaccination program, the World Health Assembly declared the fatal disease eradicated in 1980. With a large amount of the world's population no longer immune to smallpox, however, an intentional release of the virus among military personnel or the general public could have a devastating global impact.Current smallpox research focuses on developing vaccines, drugs and diagnostic tests to protect against the virus should it be used as an agent of bioterrorism. JYNNEOS was developed as an alternative to the current U.S. licensed smallpox vaccine, ACAM2000, which cannot be used by people with certain health conditions.To assess the vaccine's effectiveness, USAMRIID study director Phillip R. Pittman, M.D., led a clinical trial in collaboration with the U.S. Defense Health Agency (DHA). His team enrolled U.S. service members stationed in South Korea in the study, placing 440 participants into one of two groups. While the first group received two doses of JYNNEOS 28 days apart, the second group received a single dose of ACAM2000. Participants receiving JYNNEOS had a superior immune response and fewer side effects compared to those who received ACAM2000.While enhancing the medical readiness of U.S. fighting forces, the new smallpox vaccine also has been selected for inclusion in the Centers for Disease Control and Prevention's (CDC) Strategic National Stockpile, the nation's largest supply of potentially life-saving pharmaceuticals and medical supplies for use in a public health emergency.About Smallpox Smallpox is an ancient disease that is highly contagious and often fatal in humans. Symptoms include fever, body aches, and a skin rash that develops into fluid-filled lesions. The smallpox virus is spread through saliva and droplets from the respiratory tract, or by direct or indirect contact with the virus as it is shed from skin lesions. The virus also can be spread through other body fluids and contaminated clothing or bedding.About Monkeypox Monkeypox is a rare disease that does not occur naturally in the U.S. It begins with fever, headache, muscle aches and exhaustion and is typically milder than smallpox, though it can be fatal in some cases. Monkeypox is transmitted to people from wild animals, such as rodents and primates. In 2003, the U.S. experienced an outbreak of monkeypox, which was the first time human monkeypox was reported outside of Africa.About USAMRIID USAMRIID is celebrating its 50th year of providing leading edge medical capabilities to deter and defend against current and emerging biological threat agents. The Institute is the only laboratory in the Department of Defense equipped to safely study highly hazardous viruses requiring maximum containment at Biosafety Level 4. Research conducted at USAMRIID leads to medical solutions--vaccines, drugs, diagnostics, and information--that benefit both military personnel and civilians. Established in 1969, the Institute plays a key role as the lead military medical research laboratory for the Defense Threat Reduction Agency's Joint Science and Technology Office for Chemical and Biological Defense. USAMRIID is a subordinate laboratory of the U.S. Army Medical Research and Development Command. For more information: