Smart travelers know that immunizations are as important as having a passport when traveling to other countries. It is important that travelers contact a travel health expert up to six months in advance of their trip to ensure there is enough time to receive any needed shots. According to Julia Dyer, a gastroenterologist and public health specialist who operates the Travel Medicine Clinic in Chicago's Loop, two common travel-related shots are hepatitis A and tetanus. Depending on where travelers are going, immunizations like those against polio, hepatitis B, Japanese encephalitis, and yellow fever are also important to remember. Travelers should understand that all immunizations cannot be given on one day, that the vaccines need a few days to take effect, noted Valerie Gongaware of Northwestern Memorial Hospital's Travel Immunization Center in Chicago. "Most vaccines, even the non-serious ones, take a minimum of 10 days to two weeks to become effective," she said.