(Candid1) was developed at the US Army Medical Research Institute for Infectious Disease (USAMRIID) at Ft. Detrick, MD in the 1980s which has shown to be safe, well tolerated and effective in reducing mortality and morbidity due to AHF. The vaccine, which came from an XJ strain of the Argentinian mammarenavirus, was continually passaged a total of 44 times in newborn mouse brains, and a total of 19 times along with cloning in FRhL cells. Over 90% of the volunteers in Phase 1 and 2 clinical trials developed antibodies against the Argentinian mammarenavirus, and 99% developed an adequate immune response specific for Argentinian mammarenavirus. Moreover, a large efficacy study among 6,500 people, where 3,255 individuals were randomly selected to take Candid 1 and 3,245 individuals were randomly selected to take a placebo resulted in 23 cases of Junin-like infections, where 22 out of the 23 cases were from the placebo group. This efficacy study resulted in a 95% vaccine efficacy. Currently, the Candid 1 vaccine, otherwise known as the Junin vaccine, is licensed in Argentina by the regulatory agency of Argentina where Argentinian mammarenavirus is endemic to the region. People in laboratories who come in constant contact with Argentinian mammarenavirus are also recommended to take the Junin vaccine to prevent transmission. References Arenaviridae Rodent-carried diseases