It is now detected all over the world.
A first case of the Omicron variant has been confirmed in the United States in a fully vaccinated individual returning from South Africa, US health officials said on Wednesday.
The person, who tested positive in California, "had mild symptoms that were improving," the Centers for Disease Prevention and Control (CDC) said in a statement.
"All people in close contact (with this person) have since tested negative," they added, adding that the individual tested positive had returned from South Africa on November 22, two days before this country does not signal the appearance of the new variant.
He was then tested positive Monday, November 29, before the genome of the virus was sequenced.
"We know what we have to do to protect the population: get yourself vaccinated if you are not already vaccinated, remind you if you have been vaccinated," called Dr Anthony Fauci, executive adviser on the health crisis, shortly after the announcement.
It was "only a matter of time"
Omicron has already been detected in twenty countries, and confirmation of its presence in the United States was "only a matter of time," said Jeff Zients, coordinator of the fight against the pandemic at the White House.
Washington has since Monday banned the entry into US territory of travelers arriving from eight southern African countries, a measure criticized by these countries, but also the head of the UN.
Faced with the Omicron variant, the world is barricaded
"We see this as a temporary measure," said Anthony Fauci, repeating that it was introduced in order to buy time to prepare for the new variant.
“No one thinks (…) that a travel ban will prevent infected people from returning to the United States,” he added.
At this time, all foreign adults entering the United States must be vaccinated, but also have tested negative within three days before flying.
Americans returning from abroad must also be tested, one or three days before their departure depending on their immunization status.
A disturbing variant
The US government wants to reduce the deadline to one day for everyone.
He is also considering mandatory post-arrival testing and quarantine measures, which are only recommended for now.
Omicron has been classified as "of concern" by the World Health Organization (WHO).
To read also Omicron: where was really born this variant which anguishes the planet?
It worries experts because it has many mutations that are likely to make it more contagious, or more resistant to the immunity conferred by vaccines.
Studies are underway to determine if this is indeed the case, and to what extent, but the first results should only be available in the coming weeks.