Vaccinations for South Africa
The one vaccination certificate you may be required to show at immigration is yellow fever, and then only if you arrive from or via the yellow fever belt of Africa or South America.
Other recommended vaccinations are tetanus and polio. You could also consider immunisation against hepatitis A and B, diphtheria, rabies, typhoid, cholera and tuberculosis.
That said, please ensure that you always check with your local travel clinic or doctor before traveling, as there are different guidelines depending on the country you are traveling from.