From just over 200 new confirmed cases per day in recent weeks, South Africa saw the number of new daily cases rocket to 2,465 on Thursday. Struggling to explain the sudden rise in cases, scientists studied virus samples from the outbreak and discovered the new variant.

In a statement on Friday, the WHO designated it as a "variant of concern," naming it "omicron" after a letter in the Greek alphabet.

After convening a group of experts to assess the data, the U.N. health agency said that "preliminary evidence suggests an increased risk of reinfection with this variant," as compared to other variants.

"The number of cases of this variant appears to be increasing in almost all provinces in South Africa," the WHO said.

EXPLAINER: What is this new COVID variant in South Africa?

What we know about Omicron variant that has sparked global alarm