Despite the latest sporadic cases of yellow fever detected in the northern regions of Kenya, and despite the fact that it is still present in the country, although with much less risk factor than other African nations, the vaccine for this viral disease carried by mosquito bites, is not required for those who are going to travel to Kenya.
Therefore, a vaccination certificate for yellow fever is not mandatory for those who must travel to Kenya, unless the traveler has recently (within 15 days) visited a country defined as high-risk and for which the certificate is mandatory.
ATTENTION! However, just spending more than 12 hours in airport transit in a high-risk country is enough to be refused entry to Kenya by immigration authorities or to be denied boarding from the country of departure.
For example, Ethiopia being a risk country according to the World Health Organization, if you miss a connecting flight and have to spend more than half a day in Addis Ababa, you would need to get the vaccine to make sure you can depart.
Vaccination for yellow fever, for some years, lasts a lifetime so its certificate (yellow as the name of the disease) is also valid forever.
As far as Kenya is concerned, it is recommended for those who intend to go on safari in areas that are not restricted and heavily traveled (e.g. Turkana, Samburu, Wajir desert, Lake Victoria islands) or go to remote villages and rural areas for work or volunteer work.
These are the African nations considered at high risk: Angola, Benin, Burkina Faso, Burundi, Cameroon, Central African Republic, Chad, Republic of the Congo, Democratic Republic of the Congo, Ivory Coast, Equatorial Guinea, Ethiopia, Gabon, Gambia, Ghana, Guinea, Guinea-Bissau, Kenya, Liberia, Mali, Mauritania, Niger, Nigeria, Senegal, Sierra Leone, Southern Sudan, Sudan, Tanzania, Togo and Uganda.
A curiosity: South Africa asks for the certificate of vaccine for yellow fever to citizens, residents or tourists transited for more than 12 hours in Kenya.