If you're an adult, you won't need any inoculations unless you're
travelling from a yellow-fever endemic area (the yellow fever belt of
Africa or South America), in which case you will need certification to
prove your inoculation status when you arrive in South Africa.
It is recommended that you have the required inoculations four to six
weeks before you travel to South Africa (a yellow fever inoculation
certificate only becomes valid 10 days after inoculation - after which
it remains valid for 10 years).
Hepatitis B inoculations are recommended for children up to the age of
12 who have not completed the series of injections as infants. Booster
doses for tetanus and measles can also be administered.
Read more:
http://www.southafrica.info/travel/advice/healthtips.htm#ixzz1qVA1jFj1