Prof Salim Abdool Karim, one of South Africa's top infectious disease epidemiologists, has said that existing COVID-19 vaccines are probably effective at preventing severe disease from the newly identified variant, BBC News reported on Monday.

Karim added that it was too early to say whether Omicron leads to more severe clinical symptoms than previous variants.

At an online health ministry press briefing, Prof Karim was quoted as saying that closing borders had almost no benefit.

The variant is likely to fuel a surge in South Africa's COVID-19 cases this week that could see infections treble.

"I am expecting we will top over 10,000 cases by the end of the week per day," Prof Karim added.