It's easy to feel safe on a cruise, especially if you stick to well-touristed areas and don't eat or drink local foods in port. In this way, you might feel one step removed from exposure to communicable diseases commonly found in the countries you visit by ship. That feeling of safety is justified to a certain extent, but there are still risks that might require you to get a few jabs before you leave home.
For example, adventurous outdoor activities carry a risk from insect and animal bites in some locations, as do tattoos and piercings almost anywhere. Regardless of what you plan to do in port, there may be vaccines that are required for entry into certain countries, even when you arrive by cruise ship. You should plan to get vaccines that are required and/or recommended at least a month before your travel dates.
In addition to vaccines required by individual countries, the U.S. Centers for Disease Control and Prevention (CDC) issues guidelines for vaccinations that are recommended for travel, with special information for cruisers, as well as for children and travelers with compromised immune systems.
At the top of its list for travelers to all destinations are vaccinations for measles (MMR). Flu shots and routine childhood immunizations, including the diphtheria-pertussis-tetanus vaccine (DPT), varicella (chickenpox) vaccine, and polio vaccine are all recommended by the CDC before travel. (Because these are standard for all travelers, we will not repeat them in the individual listings below.)
Here's a rundown of which vaccines are required where, plus those you may want to consider before your next cruise. Keep in mind that cruise lines might not notify you of required vaccines before sailing.