COVID-19 cases in South Africa have nearly doubled in a day, with new confirmed cases reaching 8,561, authorities reported Wednesday.

The report follows growing concern around the new Omicron variant and what it could mean for a continent where only 10% of the population received one dose of a COVID vaccine.

“There is a possibility that really we’re going to be seeing a serious doubling or tripling of the cases as we move along or as the week unfolds,” Dr. Nicksy Gumede-Moeletsi, regional virologist for the World Health Organization, told the Associated Press. “There is a possibility that we are going to see a vast increase in the number of cases being identified in South Africa.”

Health officials say it's too early to be certain that the Omicron variant is responsible for the rise in cases. Standard PCR tests can suggest that a positive case is caused by Omicron, but only a full genetic sequencing can confirm it, according to the AP.

“The current data that we’re having is still very limited. So there are so many additional characteristics of this virus that the researchers are busy studying, of which transmissibility is one of them. Severity is also another,” Gumede-Moeletsi said.

Experts also do not know if current vaccines will still be effective against the new variant.

Omicron has been detected in Australia, Belgium, Canada, Germany, Italy, the Netherlands, Portugal, the U.K. and other countries. It has also been detected in Israel and Hong Kong.

Scientists have cautioned that it is still unclear whether Omicron is more dangerous than other versions of a virus that has killed more than 5 million people worldwide, NBC News reported.

However, the World Health Organization on Monday warned that the new Omicron variant has a “very high” global risk and urged national authorities to step up pandemic relief efforts. 

Meanwhile, the Centers for Disease Control and Prevention on Monday strengthened recommendations for the COVID-19 booster shot following the rise of the new Omicron variant. 

Chinese President Xi Jinping has also responded to the rise of the variant in South Africa and announced that China will donate another billion doses of vaccines to Africa to help curb vaccine inequity and protect people from the new wave of cases on the continent.