If your summer plans include an international vacation, here's a good review article on vaccines and travel health:
Immunizations prior to travel contribute to reducing the risk of specific diseases for the traveler as well as the risk of international spread of diseases. Environmental and host factors determine the risk of acquiring a disease while traveling. Most relevant in the first group of factors are the location to be visited, duration of travel, and reason for travel. Among host factors, the health of the traveler and his or her expected behavior abroad need to be considered.