With a large youth population and the world's biggest HIV caseload, the announcement affects millions of people and marks a significant scaling up of South Africa's pandemic response.

"We ready to open up vaccination for children between 12-17 years of age, and a majority of this cohort are in the secondary or high school level," Health Minister Joe Phaahla told a news conference.

Under South African law, children aged 12 and up can give their own consent for medical treatment, meaning they don't need parental permission to get the vaccine.

Starting Wednesday, children can receive a single Pfizer dose, with a second shot delayed to allow for further study on a rare side effect, the minister added.

More than one third of all adults in South Africa have received at least one dose of a Covid-19 vaccine, the minister added.

The country has launched a digital vaccine certificate scheme. Proof of vaccination is required to enter larger gatherings such as sporting events.

For the immune compromised, Phaahla said they can begin receiving boosters, but only on advice from their doctor.