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

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.

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

The FDA has expanded its emergency authorization for Eli Lilly's monoclonal treatment for the treatment of mild to moderate COVID-19 to children under 12, including newborns, who have tested positive and are at risk for getting severely ill. This expansion also includes preventative use in young kids who may have been exposed and who are at high risk of getting severely ill. 

This is the first time a monoclonal treatment has been authorized for children under 12.

-ABC News' Sasha Pezenik

Three cases of the omicron variant have been detected in Maryland, all among Baltimore area residents, Gov. Larry Hogan said.

One of these people, who is vaccinated, recently traveled to South Africa. The second case is someone in their household who is not vaccinated, Hogan said.

The third case is unrelated; this person, who is vaccinated, has no recent travel, Hogan said.

No one required hospitalization, he said.