Yellow fever population is vaccinated. Control of the yellow fever mosquito "A. aegypti" is of major importance, especially because the same mosquito can also transmit dengue fever and chikungunya disease. "A. aegypti" breeds preferentially in water, for example in installations by inhabitants of areas with precarious drinking water supply, or in domestic waste, especially tires, cans, and plastic bottles. These conditions are common in urban areas in developing countries. Two main strategies are employed to reduce mosquito populations. One approach is to kill the developing larvae. Measures are taken to reduce the water accumulations in which the larvae develop. Larvicides are used,
Yellow fever outbreaks, fractional dosing of the vaccine is being considered as a dose-sparing strategy to maximize limited vaccine supplies. Fractional dose yellow fever vaccination refers to administration of a reduced volume of vaccine dose, which has been reconstituted as per manufacturer recommendations. The first practical use of fractional dose yellow fever vaccination was in response to a large yellow fever outbreak in the Democratic Republic of the Congo in mid-2016. In March 2017, WHO launched a vaccination campaign in Brazil with 3.5 million doses from an emergency stockpile. In March 2017 the WHO recommended vaccination for travellers to certain parts of