<P> Blood testing to verify that the vaccine has worked is recommended in those at high risk . Additional doses may be needed in people with poor immune function but are not necessary for most people . In those who have been exposed to the hepatitis B virus but not immunized, hepatitis B immune globulin should be given in addition to the vaccine . The vaccine is given by injection into a muscle . </P> <P> Serious side effects from the hepatitis B vaccine are very uncommon . Pain may occur at the site of injection . It is safe for use during pregnancy or while breastfeeding . It has not been linked to Guillain--Barré syndrome . The current vaccines are produced with recombinant DNA techniques . They are available both by themselves and in combination with other vaccines . </P> <P> The first hepatitis B vaccine was approved in the United States in 1981 . A recombinant version came to market in 1986 . It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system . As of 2014, the wholesale cost in the developing world is US $0.58--13.20 per dose . In the United States it costs US $50--100 . </P> <P> Hepatitis B vaccination, hepatitis B immunoglobulin, and the combination of hepatitis B vaccine plus hepatitis B immunoglobulin, all are considered as preventive for babies born to mothers infected with HBV . The combination is superior for protecting these infants . The vaccine during pregnancy is not considered to be valuable in protecting babies of the infected mothers . Hepatitis B immunoglobulin before birth has not been well studied . </P>

When did the hepatitis b vaccine come out