Programs that provide inoculations that protect at risk populations including sexually active gay/bisexual men, injecting and non-injecting drug users, health care workers and heterosexuals who have multiple sex partners from contracting hepatitis B, an inflammation of the liver. Hepatitis B vaccine is also recommended for all adolescents who may not have received it during infancy or childhood. The vaccine is administered in a three-dose regimen over a period of six months.