Five cases of the new COVID-19 variant omicron have been detected in New York state, Gov. Kathy Hochul announced in a press conference Thursday evening.

Hochul emphasized that battling the delta variant is more of a challenge right now, adding that all five cases have been described as mild.

One case was located in Suffolk County, while three others were in New York City -- two in Queens and one in Brooklyn, Hochul said. A fifth suspected case has also been detected, the governor said, but did not provide details.

-ABC News' Will Gretsky

New York City's latest health mandate will require all nonpublic school employees to be vaccinated by Dec. 20, affecting 56,000 employees of 930 yeshivas, Catholic schools and other private schools.

-ABC News' Aaron Katersky

A woman who lives in Arapahoe County, Colorado, has tested positive for the omicron variant of COVID-19, the state's department of health said.

She recently traveled to southern Africa and has "minor symptoms."

She is fully vaccinated but has not yet received the booster, the department said.

President Joe Biden on Thursday announced his plan to fight COVID-19 this winter, including expanding booster access, expanding vaccine access for kids, offering free at-home rapid tests, extending the mass mandate for public transit and testing international travelers.

Biden said "all inbound international travelers must test within one day of departure, regardless of their vaccination status or nationality."

"This tighter testing timetable provides an added degree of protection as scientists continue to study the omicron variant," he said.

Biden said he is requiring health insurers to cover the cost of at-home COVID-19 tests.

"Private insurers already cover the expensive PCR test that you get in a doctor's office, and now they will cover at-home tests, as well," he said. "For those not covered by private insurance, we're going to make available free tests at thousands of convenient locations."

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."