The Food and Drug Administration (FDA) implemented a ban against men who have sex with men (MSM) from donating blood. This ban was implemented in fear that HIV would inadvertently be spread through blood transfusions at the onset of the HIV epidemic when HIV/AIDS was still largely not understood. Under the ban, no man who has had sex with another man even once since 1977 is allowed to donate blood. The ban was lifetime from September 1985 until December 2015, where it was reduced to a 1 year gap since the last sexual encounter with another man.