Before hepatitis A virus (HAV) was identified, spread of
hepatitis A was prevented by public health measures. The first specific, preventive measure for
hepatitis A was passive protection with standard, pooled human
immune globulins. Human
immune globulin contained sufficient HAV
neutralizing antibodies for short-term, prophylactic passive protection and for control of the spread of local outbreaks. After many unsuccessful attempts, HAV was propagated in cell cultures and the development of
vaccines for active immunization began.
Formalin-inactivated, whole HAV induced protective immunity, and such
formalin-inactivated
hepatitis A vaccines are now being evaluated in large-scale clinical trials. HAV attenuated by serial propagation in cell culture has been used for several, live, attenuated
hepatitis A vaccines and results of clinical trials are reassuring. Future approaches to protection against
hepatitis A are likely to include vaccination with: hybrid viruses; hepatitis A
antigen-expressing, genetically-engineered bacteria; purified
hepatitis A antigens produced by molecular
biological techniques and incorporated into slow or pulse-releasing systems; synthetic
peptides or idiotypes.