People infected with earlier variants of Covid do not appear to be protected against Omicron, although vaccination will still prevent serious illness, a top South African scientist said .

“We believe that previous infection does not provide protection from Omicron,” said Anne von Gottberg, an expert at the National Institute for Communicable Diseases.

Outlining early research into the newly-emerged variant, she said doctors were seeing “an increase for Omicron reinfections.”

This trend was also seen in models which projected those cases against the overall population, she said in a news conference with the World Health Organization’s Africa region.

“We believe the number of cases will increase exponentially in all provinces of the country,” she said.

“We believe that vaccines will still however protect against severe disease,” she added.

“Vaccines have always held out to protect against serious disease, hospitalisations and death.”

The new variant, first reported to the WHO a week earlier, has popped up across continents.

WHO experts reiterated calls for a rethink on travel bans against southern Africa, given that Omicron had now been reported in nearly two dozen countries and its source remained unclear.

“South Africa and Botswana detected the variant. We don’t know where the origin of this could have been,” said specialist Ambrose Talisuna. “To punish people who are just detecting or reporting… is unfair.”

In mid-November, South Africa was reporting about 300 cases a day. On Wednesday the country reported 8,561 new cases, up from 4,373 the day before and 2,273 on Monday.