As of October 2022, no vaccination is required to travel to Kenya.
As is known, there is no vaccine for malaria and experts advise against prophylaxis.
Kenya, unlike Tanzania and Ethiopia, does not require a yellow fever vaccination card, which, moreover, for some years now has no expiry date and lasts a lifetime. Only if you have been in the previous 15 days in a country where yellow fever is active and Kenya requires vaccination from those coming from there (Ethiopia yes, Tanzania no, to give an example) is it compulsory to present it.
This does not apply to airports where you only transit and stay for less than 12 hours.
No other vaccinations are currently required in Kenya.

THE RULES FOR COVID 19

If you are not fully or even partially vaccinated, or if you have had Covid-19 and recovered from it but have not had the opportunity or time to vaccinate, you may enter Kenya, but under certain conditions.

For example, if you have had COVID-19 within the last 90 days you can enter without vaccination, with a simple PCR swab with a negative result, taken no later than 72 hours after departure.
On arrival, in the case of checks revealing fever lines, you may be asked to take an antigen test at your own expense ($30) and in the case of a positive result a PCR swab.

FOR CHILDREN UNDER THE AGE OF 18

Children under the age of 4 need neither vaccination nor a negative PCR test to enter Kenya.

Children under the age of 17 do not need a COVID-19 vaccination to enter Kenya, but if they are not vaccinated they must show a negative PCR swab certificate, taken within 72 hours of departure for Kenya.

(Source: Main international embassies in Kenya)