Abstract
Over the last few decades, different types of inactivated hepatitis A virus (HAV) vaccines have been developed: several aluminum-adjuvanted vaccines and an aluminum-free, virosome-formulated vaccine. Both types of vaccines are whole-virus preparations that are produced by growth of HAV strains in human diploid cell cultures and are subsequently inactivated with formaldehyde. This review summarizes all published papers on a virosome-formulated vaccine, Epaxal®, based on formalin inactivated HAV (strain RG-SB) adsorbed to the surface of special liposomes (virosomes), that replace aluminum hydroxide as the adjuvant principle. A single injection of virosomal HAV vaccine is well tolerated and highly immunogenic, with 88–97% of seroprotection 2 weeks after a first dose. HAV virosomal vaccine can be administered concomitantly with other vaccines, without inducing antigenic competition. Direct comparison with aluminum-adsorbed vaccine has shown that the immunogenicity was similar, but fewer local reactions were reported with Epaxal. Recent studies in children have demonstrated that Epaxal Junior is also an excellent HAV vaccine for mass vaccination programs.
Acknowledgements
The author thanks Monika Griot-Wenk and Christian Herzog from Berna Biotech for their comments on the manuscript.
Financial & competing interests disclosure
PA Bovier has received speaker fees from Berna Biotech to present the results of different clinical studies with the virosomal vaccine hepatitis A vaccine in the past 10 years: 1997 (Hepatitis A vaccine: current trends, 5th International Conference on Travel Medicine, Genève, Suisse), 2000 (Clinical experience with an inactivated virosome formulated hepatitis A vaccine, 10th European Congress of Clinical Microbiology and Infectious Diseases, Stockholm, Suède), 2003 (Evolution of vaccines against hepatitis A : from the classic adjuvant to the new adjuvanted vaccines, Symposium on New Technological Platforms in the Development and Production of Vaccines organised by Berna Biotech, Edinburgh, Scotland) and 2006 (Advances in travel vaccination: virosomal hepatitis A vaccine, Northern European Conference on Travel Medicine 2006, Edinburgh, Scotland). The author has no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.
No writing assistance was utilized in the production of this manuscript.