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

South Korea on Wednesday confirmed its first cases of the omicron variant.

The Korea Disease Control and Prevention Agency said the new variant was initially detected among three people -- a couple who arrived from Nigeria on Nov. 24 and their friend who drove them home from the airport. Since then, the variant was found in two other people who also traveled to Nigeria and returned to South Korea on Nov. 23, bringing the total of confirmed cases to five.

Health authorities are conducting genetic sequencing tests on the couple's child and relatives of the friend who drove them home to determine if they were also infected, according to the Korea Disease Control and Prevention Agency.

In an effort to fend off the omicron variant, which was first identified in southern Africa last week, South Korea has banned foreign short-term travelers from eight southern African nations. South Korean citizens arriving from those countries must quarantine for at least 10 days, regardless of their vaccination status.

South Korea's daily tally of newly diagnosed COVID-19 infections exceeded 5,000 on Wednesday for the first time since the start of the pandemic. The surge, which officials attributed to the highly contagious delta variant, has pushed COVID-19 hospitalizations and deaths in the country to record highs.

The Korea Disease Control and Prevention Agency said most of the 5,123 new cases were reported in the capital, Seoul, and its surrounding metropolitan region, where officials said earlier that more than 80% of intensive care units designated for COVID-19 patients were already filled.

-ABC News' Joohee Cho

Nigeria confirmed on Wednesday its first cases of the omicron variant.

The new variant was detected among three people with a recent history of travel to South Africa who tested positive for COVID-19 after arriving in the Nigerian capital, Abuja, according to the Nigeria Center for Disease Control.

"These cases were recent arrivals in the country in the past week," Dr. Ifedayo Adetifa, director-general of the Nigeria Center for Disease Control, said in a statement Wednesday. "Follow up to ensure isolation, linkage to clinical care, contact tracing and other relevant response activities have commenced. Arrangements are also being made to notify the country where travel originated according to the provisions of the International Health Regulations."

Following confirmation of the variant on Nigerian soil, the national travel advisory was revised and now requires all inbound travellers to present proof of pre-booked day 2 and day 7 COVID-19 tests as well as a a negative test result that was taken no more than 48 hours before departure. All outbound passengers, regardless of the requirements of the destination countries, are expected to present evidence of full COVID-19 vaccination or a negative test result done no later than 48 hours before departure.

"The NCDC assumes Omicron is widespread globally given the increasing number of countries reporting this variant," Adetifa said. "Therefore, it is a matter of when, not if, we will identify more cases."

The cases of omicron in Nigeria are also the first to be confirmed in West Africa.

-ABC News' James Bwala

The Centers for Disease Control and Prevention said Tuesday it is working to change its international travel guidelines to require COVID-19 testing one day before departure to the U.S. in light of the omicron variant. 

"CDC is working to modify the current Global Testing Order for travel as we learn more about the Omicron variant; a revised order would shorten the timeline for required testing for all international air travelers to one day before departure to the United States," the CDC said in a statement. "This strengthens already robust protocols in place for international travel, including requirements for foreign travelers to be fully vaccinated." 

The CDC continues to recommend that all travelers get a COVID-19 viral test three to five days after arrival in the U.S. and that unvaccinated travelers quarantine for seven days even if they test negative. 

-ABC News' Cheyenne Haslett

Pfizer has officially requested Food and Drug Administration authorization of its COVID-19 booster for 16- and 17-year-olds, the company's CEO said Tuesday evening.

"It is our hope to provide strong protection for as many people as possible, particularly in light of the new variant," Albert Bourla tweeted, referring to omicron, a recently discovered variant of concern, according to the World Health Organization.

-ABC News' Sony Salzman