RABIES VACCINES - A REVIEW OF PROGRESS TOWARDS IMPROVED EFFICACY AND SAFETY

Over the years, the technology for producing human rabies vaccines has undergone many improvements, These improvements consist in the use of tissue cultures for the production of viral antigens, replacing the f ormer nervous tissue substrate vaccines. The low virus yields in tissu e cultures led to the development of the concentration and purificatio n of virus supernatants. Another technical improvement was obtained by using microcarriers for virus production in VERO cell suspension cult ures. This technique permits commercial-scale production of rabies vac cine, lowering production costs and thus extending the availability of the vaccine to a broader population in developing countries. Besides improvements in rabies vaccine production technology, the use of vario us vaccination regimens and routes of administration in field trials h as resulted in considerable gains in our experience of postexposure tr eatment (PET) of this disease. The standard WHO recommended regimen fo r PET using concentrated and purified tissue culture vaccines consists of a 5-dose course of intramuscular injections at days 0, 3, 7, 14 an d 28. Reduced vaccination regimens such as the 2-1-1 have been proven to be efficient in raising protective antibody responses. Reduction in the total volume of rabies vaccine is also possible by using the intr adermal route of injection, provided the vaccine is administered at se veral sites. The overall consequence is a progressive shift in the wor ldwide use of rabies vaccines from those of nervous tissue origin to t he contemporary tissue culture vaccines.