Omicron has become the most dominant coronavirus variant in South Africa, and at least nine omicron cases have now been reported in five U.S. states. But while an omicron surge is likely coming, experts say it's too early to know how this variant-driven wave might compare to others.

The omicron variant: The 'good,' 'bad,' and 'ugly' scenarios

Omicron spreads worldwide

The omicron variant has become the most prevalent variant of the coronavirus in South Africa, health officials reported Wednesday.

Almost 75% of the 249 samples genetically tested in South Africa in November have contained the omicron variant, according to the country's National Institute for Communicable Diseases (NICD).

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On Wednesday, South Africa reported 8,651 new Covid-19 cases, almost double the number of the previous day and a significant rise from the 116 new cases reported on Nov. 8, when the first omicron case was detected in the country.

Hundreds of cases involving omicron have been reported in Europe, and early evidence suggests the variant "may have a substantial growth advantage of the delta" variant, according to the European Center for Disease Prevention and Control.

"If this is the case, mathematical modeling indicates that the omicron [variant] is expected to cause over half of all" Covid-19 cases in the European Union "within the next few months," the agency said.

Meanwhile, multiple cases of the omicron variant have been reported throughout the United States. The first case was reported in California, five cases have been reported in New York, as well as one case each in Minnesota, Colorado, and Hawaii. According to New York health officials, all of the omicron cases in the state so far have been mild and the patients are recovering at home.

Will the omicron surge be worse than delta?

Experts say it's still too early to tell exactly how transmissible, virulent, and able to avoid immune protection the omicron variant is, but there is cause for concern.

Officials in South Africa said omicron cases have ranged from "mild disease all the way to severe disease," though no deaths from omicron have been reported yet.

Tulio de Oliveira, director of the KwaZulu-Natal Research and Innovation Sequencing Platform, said the omicron variant "seems to cause much more breakthrough infections than the previous ones." However, he cautioned against comparing omicron to delta just yet. Omicron may supplant delta as the dominant variant in countries where delta was fading, but it might not do the same in countries where delta is still spreading, de Oliveira said.

However, Leong Hoe Nam, an infectious disease doctor at Mount Elizabeth Novena Hospital in Singapore, predicted the omicron variant will "dominate and overwhelm the whole world in three to six months."

Nam said he doesn't believe drugmakers will be able to "rush out" vaccines specifically targeting omicron in time "and by the time the vaccines come, practically everyone will be infected [with] omicron given this high infectious and transmissibility."

Anne von Gottberg, head of South Africa's NICD's respiratory diseases laboratory, said, "We believe the number of cases will increase exponentially in all provinces of the country … We believe that vaccines will still, however, protect against severe disease."

But von Gottenberg also said previous infection may not offer the same defense. "Previous infection used to protect against Delta, and now with Omicron it doesn't seem to be the case," she said. (Chutel/Engelbrecht, New York Times, 12/1; Lawler, Axios, 12/2; Ng, CNBC, 12/2; McCarthy, New York Times, 12/3; Young, Politico, 12/2; Treisman/Franklin, NPR, 12/2; Chutel/Pérez-Peña, New York Times, 12/2; Steinhauser et. al., Wall Street Journal, 12/2)