Recommended Vaccines: Boosters for tetanus and diphtheria, measles/mumps/rubella, and vaccines for typhoid and hepatitis A are recommended. Yellow fever is not a risk, but you will have to show proof of vaccination if you have come from a country with high incidence of yellow fever.
Malaria: All rural areas below 1,969 feet (600 m), except on Bohol Island, Borocay Island, Catanduanes Island, and Cebu Island present a risk. Subic Bay is a risk area. Take Lariam, Malarone, or doxycycline as a preventive measure. Protect yourself against insect bites too.
Other Issues: Japanese encephalitis vaccine is suggested if you will be staying for longer than a month in the Philippines, especially if you will be visiting rural areas or participating in outdoor activities after dusk.