There are no specific vaccine requirements needed to enter Tanzania from the United States.  However, be aware that the government of Tanzania requires proof of yellow fever vaccination. This is due upon arrival if you are traveling from a country with a risk of yellow fever. If you fly directly from the United States to Tanzania (including layovers in which you do not exit the airport) you will not need the yellow fever vaccine. However, if you are arriving from a country listed here, you will need the yellow fever vaccine.