At least 10 people on board have tested positive for the virus.
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.
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."
The White House said 2.2 million vaccine doses have been administered in the last 24 hours -- the highest single-day total since May.
