The only vaccinations required are if you are planning to go the Amazon Rainforest. If so, you need a yellow fever vaccination. Even if you are not going to the amazon I still recomend it as several other countires in Latin America require it (Brazil) and the shot lasts about 10 years.
Other traveles recomend malaria tablets but I have not heard yet of any Malaria infections.
Richard Leon
www.peruforless.com www.argentinaforless.com