I have never had any injections before travelling there, but if you are worried then perhaps you should. Your medical practicioner will no doubt tell you what is recommended, but that will likely be a belt and braces list. Avoid exposing yourself to obvious risks (food and water mostly, although the place is probably no more risky than parts of Europe and the UK) once there and go armed with inoculation against yellow fever, tetanus and at least the easiest ones against hepatitis. Enjoy your trip.