There are no mandatory vaccinations for entering Tanzania. The only case that can sometimes be an exception is
vaccination against yellow fever. A certificate of vaccination against yellow fever may be required to enter
Tanzania if you are coming after a stay in one of the countries with risk of yellow fever transmission
(e.g. Ethiopia, Kenya, Uganda). You can find a full list of these countries on the website of the International
Association for Medical Assistance to Travelers. If you just plan to have a short (less than 12 hours) layover
between flights in one of them without leaving the airport, the certificate will not be necessary.
Those arriving from the Russian Federation, Ukraine, Kazakhstan, Belarus, the USA or the countries of the European
Union have no vaccine requirements.