As the COVID-19 pandemic has swept the globe, more than 5.2 million people have died from the disease worldwide, including over 785,000 Americans, according to real-time data compiled by Johns Hopkins University's Center for Systems Science and Engineering.
Just 59.6% of the population in the United States is fully vaccinated against COVID-19, according to data from the Centers for Disease Control and Prevention.
South African health officials announced another day of increases in COVID-19 cases.
The country recorded 11,125 new confirmed cases, Sunday, which represented a 23.8% positivity rate increase, according to South Africa's National Institute for Communicable Diseases (NICD).
About 71% of these new cases were diagnosed in Gauteng province where 28 new hospitalizations were recorded Sunday, according to statements from the provincial authority. More than 1,539 people are receiving hospital treatment in the province, the provincial authority said.
South Africa has detected and confirmed 228 omicron variant cases as of Sunday afternoon, data from the GISAID variant tracker showed.
Africa's Centers for Disease Control and Prevention said roughly 24% of South Africa's population is fully vaccinated as of Sunday afternoon.
-ABC News' Christine Theodorou and Liezl Thom
At least 10 people have tested positive for COVID-19 on a Cruise Norwegian ship disembarking in New Orleans this weekend, according to the Louisiana Department of Health.
Those infected include both passengers and crew members, officials said.
The Norwegian Breakaway departed from New Orleans on Nov. 28 and stopped in Belize, Honduras and Mexico on its voyage. There are more than 3,200 individuals on board, the health department said.
The company required on-site testing in addition to proof of vaccination before boarding the vessel, according to the Port of New Orleans.
The health department said the cruise line has been adhering to appropriate quarantine and isolation protocols. In addition, everyone aboard the ship will be tested for COVID prior to disembarking.
Those who test positive for COVID-19 on the ship will either travel by personal vehicle directly to their private residence or self-isolate according to current Centers fo Disease Control and Prevention guidelines in accommodations provided by Norwegian Cruise Lines.
"The health and safety of our guests, crew and the communities we visit is our highest priority, and we will continue to take all appropriate actions to ensure their wellbeing and protect public health," a Norwegian Cruise Lines spokesperson told ABC News.
"We have identified a handful of COVID-19 cases among guests and crew onboard Norwegian Breakaway, which is scheduled to disembark in New Orleans, LA on December 5. All of the identified cases onboard are asymptomatic. In addition to requiring that 100% of guests and crew are fully vaccinated, per the Company's comprehensive health and safety protocols, we have implemented quarantine, isolation and contact tracing procedures for identified cases."
The spokesperson said the company is testing all individuals prior to disembarkation, and providing post-exposure and quarantine public health guidance by the CDC.
"Any guests who have tested positive for COVID-19 will travel by personal vehicle to their personal residence or self-isolate in accommodations provided by the Company according to CDC guidelines," the spokesperson said. "We take this matter extremely seriously and will continue to work closely with the CDC, the office of Governor John Bel Edwards, the Louisiana Department of Health as well as the city and port of New Orleans. At this time, there have been no changes to scheduled future sailings on Norwegian Breakaway. We will provide additional updates to impacted guests as appropriate."
All international travelers to the UK ages 12 and up must show proof of a negative COVID-19 test taken within two days of departure, officials announced Saturday.
The changes go into effect at 4 a.m. Tuesday and apply to all travelers, regardless of vaccination status, coming from countries that are not on the " red list," according to Health Secretary Sajid Javid.
And - from 4am Tuesday, anyone travelling to the UK from countries not on the Red List will be required to take a pre-departure test, regardless of their vaccination status. 2/3
— Sajid Javid (@sajidjavid) December 4, 2021
Previously, travelers to the UK did not have to take a COVID-19 test if they were fully vaccinated and had not been in a red list country.
UK officials also announced that Nigeria will be added to the red list, effective 4 a.m. Monday.
The changes are to "slow the incursion of the Omicron variant," Javid said on Twitter.
Over 97% of Centers for Disease Control and Prevention employees are vaccinated, according to data released Friday by the Department of Health and Human Services.
Additionally, 99% of the agency's employees are "in compliance," meaning they have either initiated vaccination or have submitted a request for a medical or religious exemption.
In other HHS divisions, 96% of Food and Drug Administration employees are vaccinated and 99% are in compliance. At the National Institutes of Health, 97% are vaccinated and 99% are in compliance.
The data release comes as some Republican senators have pushed CDC Director Rochelle Walensky for vaccination rates at her own agency as she defends Biden's federal workers vaccine mandate, which is being challenged in federal court.
-ABC News' Cheyenne Haslett
Dr. Francis Collins, the director of the National Institutes of Health, is urging Americans to be vigilant in the wake of a new variant of the novel coronavirus that is sweeping the globe.
The World Health Organization has designated omicron as a "variant of concern." But so much remains unknown about omicron, including whether it causes severe disease and if it is more contagious than delta, which is currently the dominant variant in the United States.
"We're collecting that information as rapidly as we can, and much credit to our colleagues in South Africa who have been totally transparent about this. We only learned about this one week ago from one of their sequencers," Collins told ABC News' Robin Roberts in an interview Tuesday on "Good Morning America."
"So we are quickly trying to figure out in South Africa, is this in fact more contagious than other variants? It does look like it's spreading quite quickly there," he added. "But we don't know how that would play out in a country like ours, where delta is already so dominant. Would omicron be able to compete with delta? We don't know the answer to that."
Another big question, Collins said, is whether the current COVID-19 vaccines and boosters will provide protection against omicron as they have against previous variants. The answers will "take a couple of weeks" to uncover, he said.
In the meantime, Collins encouraged all Americans to get vaccinated and boosted if eligible, and to wear face masks.
"I wear my mask if I'm indoors with other people -- I don't always know if they're all vaccinated or not. That's just good practice," he said. "I know we're all tired of this, but the virus is not tired of us and it's continuing to exploit those opportunities where we're careless."
