Antibodies are proteins that a person's immune system makes to fight germs.
IG is also known as immune serum globulin or gamma globulin. When injected into a muscle, IG can provide almost immediate, short term protection against certain illnesses, or can help make the illness less severe. IG can prevent the spread of hepatitis A among people who are in close contact with each other. IG is of no benefit when received more than 14 days after the last exposure to the hepatitis A-contagious person. To prevent disease, it should be given as soon as possible after exposure, preferably within 3 days and no later than 6 days after exposure to a case of measles.