In some months, such as October and November, the Zambezi River is very low and as the channel on the Zimbabwean side is deeper than that on the Zambian side, the falls may not actually have any water flowing over them at all from the Zambian side while the falls from the Zimbabwean side always has water! Once again this is very limited to very short periods of time, depending on weather and other factors which no one can control. Of course one can stay on the Zambian side as the program states and do a day trip across to Zimbabwe. This will require a dual entry visa for Zambia and single entry visa for Zimbabwe.
Yellow Fever Vaccinations are required for entry into Zambia and re-entry in South Africa.