The WHO classified omicron as a "variant of concern."
As the COVID-19 pandemic has swept the globe, more than 5.2 million people have died from the disease worldwide, including over 776,000 Americans, according to real-time data compiled by Johns Hopkins University's Center for Systems Science and Engineering.
Just 59.1% of the population in the United States is fully vaccinated against COVID-19, according to data from the Centers for Disease Control and Prevention.
Vice President Kamala Harris says she has been briefed on the omicron variant and when asked if there will be any additional travel restrictions, she said they will be "taking it one step at a time."
Harris said that for now, the administration believes they’ve done "what we believe is necessary," and they will "take every precaution" to protect Americans.
-ABC News' Justin Gomez
English Prime Minister Boris Johnson announced new tightened measures Saturday in response to the discovery of omicron in the UK. The measures include:
-All international arrivals entering England must take a Day 2 PCR test and self-isolate until they receive a negative result.
-All contacts of suspected omicron cases must self-isolate for 10 days, regardless of their vaccination status.
-Face coverings will become compulsory on public transport and in shops.
The UK government had also said that omicron was found in Chelmsford, but said Saturday that that information was incorrect and that the variant had been found in Brentwood.
A spokesperson for Essex County Council said: "We can confirm that a single case involving the new Covid-19 Variant of Concern (B 1.1.529) , Omicron, has been identified in Brentwood. This is linked to a single case from Nottingham involving international travel to South Africa."
“We are working with regional and local public health officers who are assessing the situation. All close contacts of these individuals will be followed up and requested to isolate and get tested," the spokesperson said in a Twitter thread.
"The individuals who have so far tested positive, as well as all members of their households, are being re-tested and have been told to self-isolate while contact tracing is underway .... While this work takes place, it is important that everyone takes sensible precautions -- get a PCR test if you have symptoms, isolate when asked, wear a face covering in crowded and enclosed spaces, ventilate rooms, get your vaccine and boosters as soon as you can," the spokesperson added.
-ABC News' Rashid Haddou
Two cases of the newly discovered variant, omicron, were detected in the UK -- in Chelmsford and Nottingham -- according to the UK Health Secretary, Sajid Javid.
The cases are linked to South Africa. Javid said four more African countries were added to the UK’s Travel Red List : Malawi, Mozambique, Zambia and Angola. Also currently on the list are Botswana, Eswatini, Lesotho, Namibia, South Africa and Zimbabwe.
-ABC News' Rashid Haddou
Chief medical adviser to the president, Dr. Anthony Fauci, said he "wouldn't be surprised" if the new COVID-19 variant omicron was already in the United States, on NBC Saturday morning.
"You know, I would not be surprised if it is. We have not detected it yet, but when you have a virus that is showing this degree of transmissibility and you're already having travel-related cases that they've noted in Israel and Belgium and other places, when you have a virus like this, it almost invariably is ultimately going to go, essentially all over," Fauci said.
"Its ability to infect people who have recovered from infection and even people who have been vaccinated makes us say this is something you have to pay really close attention to and be prepared for something that's serious. It may not turn out that way, but you really want to be ahead of it," Fauci also said.
-ABC News' Ahmad Hemingway
