Three US states have found cases of the Omicron coronavirus variant – California, Colorado and Minnesota – among patients who were fully vaccinated and developed mild symptoms, health officials say.
The Minnesota patient is the first known US case of community transmission of the Omicron variant, found in a fully vaccinated man who had recently travelled to New York City and attended a conference.
To combat the spread of Omicron, on Thursday (local time), US President Joe Biden announced new testing requirements for international travellers and promised that Americans would soon have access to free, rapid at-home COVID-19 testing.
Colorado health officials said on Thursday a woman with the Omicron variant had recently returned from a trip to southern Africa.
California reported the first US case of the variant on Wednesday, in a fully-vaccinated traveller who had been in South Africa. The new variant was first detected in southern Africa last month.
After determining the Minnesota case had a New York connection – the man attended an anime convention at New York City’s Javits Centre from November 19-21 – health officials immediately activated the “Test and Trace Corps” to contact conference attendees to try to contain the spread, New York City Mayor Bill de Blasio said.
“We are aware of a case of the Omicron variant identified in Minnesota that is associated with travel to a conference in New York City, and we should assume there is community spread of the variant in our city,” the mayor said in a statement.
Dr Leana Wen, a public health professor at George Washington University and former Baltimore health commissioner, said it was only a matter of time before more Omicron cases were detected in the US.
The Minnesota case “means that there is spread in the United States. There will be many more cases to come”, Dr Wen said on Twitter.
Scientists are investigating Omicron, which has been labelled as a variant of concern by the World Health Organisation, to see if it is more transmissible than the Delta variant that is now prevalent, and if it causes more severe disease. They are also studying how well vaccines work against it.
Minnesota Governor Tim Walz said the news of the case in the state was “concerning, but it is not a surprise”.
“We know that this virus is highly infectious and moves quickly throughout the world,” he said.
Mr Walz urged residents to get vaccinated and wear masks indoors. The best response to the new variant was the same as it had been throughout the pandemic: Get a vaccine, he said.
About 60 per cent of the total US population, or 196 million people, have been fully vaccinated. It is one of the lowest rates among wealthy nations.
More than 786,000 people have died from COVID-19 in the US, including 37,000 in November alone.