Yellow fever vaccine should be administered either at the same time as other live-virus vaccines (but at a different injection site) or at least 30 days apart.* When impractical, this recommended 30-day time interval can be adjusted, but a suboptimal immune response might occur. Consult with your state health department or CDC when considering if revaccination is needed for a traveler who may continue to be at risk.
*Note: A recent study involving the simultaneous administration of yellow fever and measles-mumps-rubella (MMR) vaccines in children found a decrease in the immune response against yellow fever, mumps, and rubella when the vaccines were given on the same day versus 30 days apart. Additional studies are needed to confirm these findings, but they suggest that, if possible, yellow fever and MMR should be given at least 30 days apart.
Oral typhoid (Ty21a) vaccine, a live bacterial vaccine, can be administered simultaneously or at any interval relative to yellow fever vaccine.
The Advisory Committee of Immunization Practices (ACIP) suggests performing tuberculin skin testing either before or on the same day that yellow fever vaccine is administered or waiting 4 weeks after administration of yellow fever vaccine before performing the skin test.