The US Army was granted a patent for a hantavirus vaccine (US Patent 5,614,193) on March 25, 1997. This development stemmed from military medical research that began during the Korean War (1950-1953), when over 3,000 cases of Hemorrhagic Fever with Renal Syndrome (HFRS) were reported among troops, leading to numerous hospitalizations and fatalities. The vaccine utilizes an attenuated vaccinia virus vector containing genes from the Hantaan virus, with lead inventor Connie Schmaljohn, a virologist at the US Army Medical Research Institute of Infectious Diseases (USAMRIID) in Fort Detrick, Maryland. The research was driven by the need for force protection as US troops are often deployed in areas where hantaviruses are endemic. Additionally, hantaviruses are considered potential biological warfare agents. The military's proactive approach filled a gap left by private pharmaceutical companies, which showed little interest in developing a vaccine due to the rarity of natural outbreaks. USAMRIID continues to work on various high-priority pathogens, including Ebola and anthrax, making this vaccine development a routine part of their biodefense efforts.