Polio vaccine
Polio virus infects the central nervous system and cause paralysis, which may be permanent. Illness in mild cases includes fever, sore throat, and gastrointestinal disturbance. Infection occurs from contaminated food and water in a very small number of countries. Travelers to risk countries should have received a 3-dose primary series, usually during childhood, and a one-time adult booster dose. The adult dose is not routinely given to non-travelers. Serious side effects are rare.