Collective Evolution: Before the introduction of the vaccine, numerous effective prevention measures had already been implemented to some degree in the US, including blood screening and administration of hepatitis B immune globulin (HBIG) to infants born to HBsAg-positive women. HBIG contains protective antibodies obtained from the blood plasma of selected donors, conferring passive immunity to the infant. It’s estimated to be about 75 percent effective in preventing chronic infection when given soon after exposure. Additionally, newborn infants may have maternal antibodies passively acquired through the placenta.
Nevertheless, the number of cases occurring in the US annually continued to increase until it peaked in 1985 at about 26,000 reported cases. The increase in prevalence was occurring particularly among young adults. The decline seen during the second half of the 1980s through the early 1990s is attributed to a reduction in transmission among gay men and drug users as a result of efforts to prevent transmission of the human immunodeficiency virus (HIV), which causes acquired immunodeficiency syndrome (AIDS). From 1990 to 2004, incidence of acute hepatitis B infection declined by 75 percent, with most of the decline occurring among children and adolescents, coinciding with greater vaccination coverage.
The hepatitis B vaccine was first licensed for use in the United States
in 1981. The following year, the CDC’s Advisory Committee on
Immunization Practices (ACIP) issued a recommendation for
vaccination of high-risk individuals. The estimated lifetime risk of
HBV infection at the time was approximately 5 percent for the US
population as a whole, but rose to almost 100 percent for the
highest-risk groups. Persons considered at “substantial risk” included
various categories of health care workers, gay men, illicit injectable
drug users, recipients of certain blood products, household and sexual
contacts of HBV carriers, Alaskan Eskimos, immigrants or refugees from
countries where HBV is highly endemic, and prison inmates....read more>>>...