Some countries need visa to visit South America. Check with your authorities if you need.
Regularly there is no obligated vaccine, it is just recommended to take the Yellow Fever at list 10 days before travelling.
Brazil: Real (BRL);
Argentina: Peso (ARS);
Uruguay: Peso (UYU);
Ecuador: American Dollar (USD);
Bolivia: Boliviano (BOB);
Peru: Nuevo Sol (PEN);
Colombia: Peso (COP).