A public health expert who gave America early warnings about Covid-19 has said that there are probably around 2,000 cases of the new omicron variant already in the US.
Dr Charity Dean, a former official at the California Department of Public Health, was among the first to warn in February last year that coronavirus was almost certainly circulating among Americans who had not travelled to China.
Now she believes that a similar thing is happening with omicron despite the US government’s claim that no cases yet exist in the country, according to an interview with Business Insider.
"I have no doubt that there are in fact cases here in the US right now," Dr Dean told the news site. "In fact, my dirty math based on a number of assumptions, including international travel – I would estimate there’s around 2,000 cases in the US right now."
It comes after chief White House medical adviser Dr Anthony Fauci said that he "would not be surprised" if the emerging omicron mutation of the virus had already reached the US via plane travel.
The Centers for Disease Control and Prevention (CDC) has said there is "no evidence of omicron in the United States", and that the delta variant still represents 99.9 per cent of all cases where the virus has been gene sequenced.
"We are actively looking for the omicron variant right here in the United States," said CDC director Dr Rochelle Walensky in a call with reporters on Monday. "Our variant surveillance system has demonstrated we can reliably detect new variants, from alpha in the start of 2021 to delta over this past summer."
Countries keep watch for new variants by sending samples from positive Covid tests to have their genetic code sequenced. However, Dr Dean told Business Inside that the US was not doing enough genomic sequencing to have spotted omicron cases reliably.
Although the US has stepped up its sequencing efforts since the start of the pandemic, it lags behind other developed nations, sequencing only 5.7 per cent of cases in the last 90 days compared to 11.5 per cent in Canada, 13.7 per cent in the UK and 28.7 per cent in Sweden.
Dr Dean said: "So many labs ramped down their sequencing efforts, understandably, throughout the Delta surge, when everything was the Delta variant."
"The challenge with having an inadequate amount of genomic sequencing in the US is it makes it much harder to detect a novel variant when it emerges."
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