The two types of vaccines contain either inactivated "Hepatovirus A" or a live but attenuated virus. Both provide active immunity against a future infection. The vaccine protects against HAV in more than 95% of cases for longer than 25 years. In the United States, the vaccine developed by Maurice Hilleman and his team was licensed in 1995, and the vaccine was first used in 1996 for children in high-risk areas, and in 1999 it was spread to areas with elevating levels of infection.