Yes you do need to get some vaccinations to go to Tahiti and it's recommended either way to prevent getting any diseases or conditions should you come in contact with them over in Tahiti.
Before going to Tahiti you need the following vaccinations such as hepatitis A, hepatitis B, typhoid, yellow fever, rabies, meningitis, polio, measles, mumps and rubella (MMR), Tdap (tetanus, diphtheria and pertussis), chickenpox, shingles, pneumonia and influenza.
So you do need to get several vaccinations which seem excessive but well worth it to prevent any sickness or other diseases.