It depends where you are going. DS2 has just returned from a World Challenge trip there and had a variety of vaccinations plus malaria tabs - but he was in Lesotho and KwaZulu Natal and trekking in the Drakensburg. If you are only going to Cape Town, you would need far fewer - if any. You should check with your GP for the current advice.
If it is just Cape Town you are going to you really shouldn't need anything. Unless you are planning to go to out of the way places and drink suspect water, in which case you might want to consider typhoid and/or cholera.
But essentially "tourist" Cape Town is regular "developed" world insfrastructure: safe water etc and you are far away from malarial areas.