Yellow Fever Vaccine Post-marketing Surveillance in Brazil

Viscerotropic disease (VD), a disease with high mortality, results from the dissemination of the yellow fever vaccine virus throughout the body. Twenty-six cases of VD following vaccination with the Bio-Manguinhos 17DD vaccine were reported, 21 from Brazil and 5 from other countries, of which 19 were confirmed, 4 probable and 3 suspect. These cases were not related to immunodeficiency diseases, but could be related to the existence of autoimmune diseases, such as systemic lupus erythematosus. Adverse neurological events following yellow fever vaccination are in general aseptic meningitis, with a good outcome, encephalitis, and autoimmune neurological events such as Guillain-Barré syndrome. In Rio Grande do Sul (2009) 2 cases of confirmed meningoencephalitis in newborns after yellow fever vaccination of a breastfeeding mother created a new and difficult problem to solve in a satisfactory manner. Bio-Manguinhos/Fiocruz is doing several studies to try to improve the yellow fever vaccine, such as a dose-response study, with the objective to know if the vaccine can be administered in a smaller dose than usual, which perhaps would be safer, Also, further purification of the current vaccine, and studies for the development of a non-live yellow fever vaccine are under way.