Fig. 5.

Population of yellow fever-suitable cities, by travel vaccination policy, 2016

Notes: In total, there were 472 yellow fever-suitable cities in 54 countries. A yellow-fever-suitable city was ecologically suitable for yellow fever virus transmission but was not located in a yellow fever-endemic area, which was defined as an area where the World Health Organization recommended yellow fever vaccination. In the urban scenario (see main text for details), there were six fewer yellow fever-suitable cities than in the base scenario: Satna, India (population 0.31 million); Ibb, Yemen (population 0.45 million); Al Hudaydah, Yemen (population 0.57 million); Taiz, Yemen (population 0.69 million); Aden, Yemen (population 0.88 million); and Sana’a, Yemen (population 2.7 million).