If you are planning a vacation overseas in the upcoming weeks or months, you should really check out the Center for Disease Control Travelers' website.
You can look up your country of destination and see what is going on health wise in the region. For example, there have been recent measles and mumps outbreaks in South East Asia. So if you are headed there you'll want to double check that all your vaccinations are in order. The Travelers' site offers a complete schedule of recommended vaccines for your travels, as well as health items you should pack, things like mosquito nets and iodine tablets.
I have found it better to be safe than sorry and that being prepared makes traveling less stressful.