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Omicron Covid variant likely circulating for longer — and more widely — than thought, experts say

Doctor wearing PPE looks on before a house-to-house coronavirus testing drive on July 21, 2020 in Lima, Peru.

Raul Sifuentes | Getty Images News | Getty Images

LONDON — As more cases of the new omicron Covid variant emerge around the world, experts say it’s likely that the variant, first identified in South Africa last week, had already been circulating for some time.

The World Health Organization said on Wednesday that at least 23 countries from five of the six WHO regions have now reported cases of omicron, “and we expect that number to grow.”

The U.S. then became the 24th country to confirm its first case of omicron. It was detected in a

Lawrence Young, professor of molecular oncology at Warwick University, told CNBC Wednesday that “it’s no surprise that omicron has been circulating more widely and for longer than has been reported previously.”

“Once a variant is identified, particularly one that is likely to be more infectious, it will have spread far beyond the few original cases and countries. That’s the nature of infectious disease in a world where international travel is so common,” he said.

Some epidemiologists have speculated that the omicron variant could have started to spread internationally around the end of October, a hypothesis agreed with by other experts spoken to by CNBC.

Paul Hunter, professor of medicine at the Norwich School of Medicine at the University of East Anglia, told CNBC Wednesday that, given the earliest known omicron sample was taken on Nov.9 in South Africa, “clearly the infection must have been circulating a little before that unless the index case was the person in whom the variant evolved, but probably not much earlier.”

While Danny Altmann, professor of immunology at Imperial College London, said he’d “certainly agree it’s a possibility” that the omicron variant was spreading earlier than November, and that there was no certainty it originate in South Africa.

“The point that it came to attention through rising cases and excellent sequencing around Gauteng [in South Africa] from the second week of November neither proves it arose near there or that this was the starting point.”

Correction: This story has been updated to reflect that the first U.S. case of the omicron variant was detected in California.

CNBC.com