Omicron updates: COVID outbreak reported on cruise ship docking in New Orleans

If a variant-specific vaccine is needed, the process, including FDA and CDC authorization, would take about three months, White House COVID-19 coordinator Jeff Zients said at Tuesday's White House briefing.

The omicron variant has still not been detected in the U.S. Delta "remains the predominant circulating string representing 99.9% of all sequences sampled," CDC director Rochelle Walensky said.

Walensky said the CDC is also working on expanding a surveillance program through JFK International Airport, San Francisco International Airport, Newark Liberty International Airport and Hartsfield-Jackson Atlanta International Airport that would conduct more tests on international arrivals. 

Walensky added, "To be crystal clear, we have far more tools to fight the variant today than we had at this time last year."

-ABC News' Cheyenne Haslett

The World Health Organization praised South Africa and Botswana on Tuesday for the "speed and transparency" in which they reported on the new omicron variant.

The WHO stressed that "blanket travel bans will not prevent the international spread, and they place a heavy burden on lives and livelihoods."

"In addition, they can adversely impact global health efforts during a pandemic by disincentivizing countries to report and share epidemiological and sequencing data," the WHO said.

South African President Cyril Ramaphosa, while on a plane to Nigeria, told reporters Tuesday that South Africa should not be "punished" with travel bans for being transparent.

"These bans must be removed," he said.

"We have advanced in the world to a point where we now know when people travel, they should be tested, like I was tested last night and I'm happy to be tested when I arrive again," he said.

"And for us, the tourism industry is one of the key industries. … This is discriminatory against us, and they are imposing a very unfair punishment," he said.

-ABC News' Christine Theodorou

About 100 million Americans remain completely unvaccinated, according to federal data. Nearly 80 million of those people are over the age of 5 and therefore eligible to get the shot.

Since the beginning of November, hospital admissions have jumped by 20%, while emergency department visits have increased by 27%, according to federal data.

Minnesota and Michigan currently hold the country's highest case rate, followed by Wisconsin, North Dakota, New Hampshire, Arizona, New York, Pennsylvania and Ohio. Puerto Rico, Florida and Louisiana currently have the nation's lowest infection rate, according to federal data.

-ABC News' Arielle Mitropoulos

Greek Prime Minister Kyriakos Mitsotakis said Tuesday that vaccines for people 60 and older will be required.

Appointments for the first dose must be booked by Jan. 19 and residents who don't comply will be fined.

There are 664 people currently hospitalized with COVID-19 in Greece and the average age of those patients is 64.

The nation's vaccination rate stands at 62%.

Greece has not yet detected a case of the omicron variant but Mitsotakis said it's just a matter of time.

-ABC News' Christine Theodorou