The below information is a distillation of information obtained from the CDC, and several medical texts. Ask your physician whether you need a booster. Reunion is not on the CDC's list of African malaria-infected countries. If arriving in Reunion from Mauritius, Mauritius is not considered an infected country. Dengue fever occurs sparodically in Reunion.
Vaccines are available.
CDC guideline would not require typhoid vaccine for our brief stay in Reunion. Drink bottled water if possible. CDC recommends vaccination for all travelers. CDC recommends vaccination for all travelers who might have need for medical or dental attention in the visited country. Since this cannot be predicted, vaccination is advised.