United States recorded its first case of COVID-19’s Omicron variant on Wednesday in California, according to a statement released by the Centers for Disease Control and Prevention.

The health department noted that the individual had a travel history to South Africa and is currently in self-quarantine. The unnamed person was experiencing “mild symptoms that are improving”.

Also Read: Omicron may turn out to be deadlier than Delta, says South African scientist

Genomic sequencing was conducted at the University of California in San Francisco and the sequence was confirmed at United States Centers for Disease Control and Prevention as being consistent with the Omicron variant.

According to statements from Dr Anthony Fauci — President Joe Biden’s top advisor on the COVID-19 pandemic, the individual was fully vaccinated against the deadly disease and returned to America on November 22 and tested positive a week later.

The Centers for Disease Control and Prevention is taking steps to tighten United States testing rules for travelers from overseas, including requiring a test for all travelers within a day of boarding a flight to the United States regardless of vaccination status. It was also considering mandating post-arrival testing.

Officials said those measures would only “buy time” for the country to learn more about the new variant and to take appropriate precautions, but that given its transmissibility its arrival in the United States was inevitable.

Also Read: Omicron: How RT-PCR tests can detect the latest COVID variant of concern

The announcement of the first United States case comes before President Joe Biden plans to outline his strategy on Thursday to combat the virus over the winter. Biden has tried to quell alarm over the omicron variant, saying it was a cause for concern but “not a cause for panic.”

Biden and public health officials have grown more urgent in their pleas for more Americans to get vaccinated — and for those who have been vaccinated to get booster shots to maximize their protection against the virus.