The National Institute for Communicable Diseases (NICD) said the measles outbreak has spread to five provinces.
The highly infectious disease was declared an outbreak by the NICD last week, recording at least 200 cases.
Almost 100 more cases have been recorded in just under a week.
This comes after Limpopo recorded the first few cases at the beginning of October. The disease has also now spread across Gauteng, Mpumalanga, Free State and the North West.
The outbreak in South Africa comes exactly one month after the World Health Organization (WHO) announced that since the pandemic, measles vaccine coverage has declined.
The organisation recorded nearly 40-million children who missed their first measles vaccine during the peak of the pandemic.
The repercussions of this are showing as the Disease Institute’s latest results show that laboratory confirmed cases range from ages two months to mid-forties. And majority of the cases are reported to be from the five to nine-year-old age group.
The respiratory disease is contagious and can lead to secondary infections like pneumonia and encephalitis which can be fatal to children.