Found this on another site. Not sure if it short term or not.

Travelers entering South Africa from World Health Organization (WHO)-designated yellow fever countries are required to present their current and valid “International Certificate of Vaccination as approved by the World Health Organization (WHO)” (commonly called a “yellow card”) or statement of medical exemption (also located on the same yellow card). Additionally, South Africa treats Zambia and Tanzania as yellow fever countries. This requirement is imposed on travelers flying to South Africa via yellow fever countries, even when transiting passengers are required to stay on board the plane (e.g., flights stopping in Dakar, Senegal or Accra, Ghana or Nairobi, Kenya), or if the plane makes an unscheduled landing in a yellow fever country. As a precaution, all travelers to South Africa should carry their original yellow card. Letters, scans, copies, or faxes regarding prior yellow fever vaccination will not be accepted. Computer printouts are not accepted. While this requirement may not be consistently applied, travelers who cannot present an original and currently valid yellow card when asked will be refused entry into South Africa. Yellow fever vaccinations are not administered at South African ports of entry for the purpose of entry into South Africa. Travelers are reminded that they are required to obtain a yellow fever vaccination at least ten (10) days prior to their arrival in South Africa in accordance with WHO regulations. South Africa may apply these requirements on people traveling from or through both high-risk yellow fever countries and low-risk yellow fever countries.

Don

My travel agent checked with SAA on this issue. At this time there is no change in the Yellow Fever policy and vacinations are not necessary if you don't disembark when transiting through other countries.

When I left Lusaka, Zambia on 11 October 2011 to Joburg, we were told prior to boarding, if your yellow fever vacinatiion was not up to date, do not get on the plane. You did have to have your yellow card. The yellow card was checked upon checking through customs in Joburg. I was flying SAA.