It may appear to be impudent to add to the vast literature on hepatitis B vaccines, a subject which has been reviewed by many recently (1-5), or to attempt to formulate policies for immunization in different countries of the world since immunization against this important infection depends on epidemiological patterns, socio-economic factors, cultural and sexual practices and the environment (Tables 1 and2). However, it is timely to take another look at some controversial issues and glimpse into the future. This was one of the major topics of discussion at a recent World Health Organization meeting organized by the Regional Office for Europe (6).
SAFETY AND EFFICACY
Many studies have provided repeated assurances on the safety and efficacy of hepatitis B vaccines derived from plasma pooled from carriers. The currently licensed vaccines conforming with WHO requirements of 1981 and the proposed requirements revised in 1983 have been shown in clinical studies in over one million vaccinated persons to be free of transmission of any infectious human pathogens, including the T lymphotropic viruses, which are the cause of some human leukemias and AIDS (7,8). Local reactions reported after immunization have been minor, occurring in less than 20% of immunized individuals and consisting of slight swelling and reddening at the site of inoculation. Temperature elevations of up to 38ยฐC were observed in only a few individuals.
PRESCREENING AND TESTING FOR IMMUNITY Immunization of immune individuals is not required, and while immunization of carriers of hepatitis B virus (HBV) is not harmful, it is ineffective and should not be performed. This would conserve the supply of vaccine and avoid unnecessary expense. Screening of individuals for HBV markers before immunization depends on the proportion of persons expected to be found positive (Table 11, the local cost of screening tests and the cost of the vaccine.
The question of which antibody or antibodies of hepatitis B should be assayed for immunity is important.
The two antibodies which are considered to indicate recovery from hepatitis B infection are hepatitis B surface antibody (anti-HBs) and hepatitis B core antibody