A Grade 9 pupil at the United Herzlia Schools in the Western Cape has tested positive for coronavirus in what is, at this stage, the first case of a child in South Africa being infected.

In a message to "parents, colleagues and pupils", the school confirmed that the child - who was not named and whose age was not provided - had gone into quarantine with her family. Her parents and older sibling had tested negative, the school said.

Earlier on Friday, the school said it would keep campuses closed until the end of the school holidays in the Western Cape, and has cancelled extramural activities after a parent tested positive for coronavirus.

At a press briefing on Friday afternoon, health minister Dr Zweli Mkhize said there were 24 confirmed cases of the virus in the country. All of them were adults who had travelled out of the country.

However, Mkhize warned that there could be further cases as they were awaiting the verification tests of other positive tests results.

In an email sent at around 11.30pm on Friday, the school said it had been notified of a new Covid-19 case.

"In this instance, the confirmed patient is a student in the Middle School in grade 9. Her sibling in Highlands Primary and both parents have all tested negative. The family is enforcing self-quarantine, and has been doing so since Thursday afternoon," the school said.

According to the US Center for Disease Control and Prevention, the symptoms of Covid-19 are similar in children and adults.

"However, children with confirmed Covid-19 have generally presented with mild symptoms. Reported symptoms in children include cold-like symptoms, such as fever, runny nose and cough. Vomiting and diarrhoea have also been reported. It is not known yet whether some children may be at higher risk for severe illness, for example, children with underlying medical conditions and special healthcare needs.

"There is much more to be learned about how the disease impacts children," it says on its website.