Yellow fever vaccine safety: a reality or a myth?

The 17D-derived yellow fever (YF) vaccines have had an excellent record of their safety among millions of recipients. Recently, extensive viral dissemination in seven vaccinees, aged 5-79 years, with just one survivor posed a serious challenge for vaccine manufacturers. Prospective evaluations of yellow fever vaccine bulk suspensions for their viscerotropism and neurovirulence in primates or an alternate animal should minimize identical viral dissemination among prospective recipients of YF vaccines.