Yellow fever (YF):

1. Hypersensitivity reactions

• Very rare
• Sensitivity to egg, which is commonly used to stabilize the vaccine, may explain at least some of these cases

2. Vaccine-associated neurotropic disease (encephalitis)

• Very rare
• Infants seem more susceptible to vaccine-associated neurotropic disease than the YF-vaccinated population at large

3. Vaccine-associated viscerotropic disease

• Very rare in children at 0.00001%
• The elderly seem more susceptible to reactions (very rare at 0.04-0.05%) than the YF-vaccinated population at large