MIAMI (CBSMiami) – It was another day of canceled flights and stranded travelers, due in large part to the highly contagious omicron variant.

Delta, United, JetBlue and American Airlines pointed to staff sick with COVID-19.

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Airlines had already cancelled hundreds of flights on Christmas Eve and Christmas Day, and more than 50 flights have already been canceled Monday.

“It actually cancelled while we were in line to check in,” said traveler Tamera Robinson.

On Christmas, Florida broke its own record for the highest number of daily cases that record set the day before, on Christmas Eve.

Los Angeles saw a 300% rise in new COVID cases last week, creating a huge demand for testing.

“I have a procedure that needs to be done, COVID testing before my procedure and now they’re telling me that they’re not doing it no more,” said Carmela Cicneros, who waited for COVID-19 Test.

The nation’s top infectious disease doctor, Anthony Fauci, acknowledged he’s frustrated by the limited supply of COVID-19 tests.

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“We’ve obviously got to do better.  I think things will improve greatly as we get into January, but that doesn’t help us today and tomorrow,” said Dr. Fauci.

Dr. Fauci says data from around the world suggests omicron may cause less serious illness, but that the variant’s high transmissibility could overwhelm the nation’s hospitals with the unvaccinated.

Hospitals in Minnesota report that’s already happening.

“If we get a huge wave of COVID, unfortunately, there’s going to be a point where we don’t have room to take care of everyone,” said Dr. Andrea Rowland-Fisher with Hennepin Healthcare.

In New York, there has been a sharp rise in the number of unvaccinated children hospitalized with COVID-19.  About half are under the age of 5 and not yet eligible to be vaccinated.

And on Monday, New York City’s new vaccine health order goes into effect.

About 184,000 private sector businesses will need to verify their workers’ proof of vaccination. There are health and religious exemptions.

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A new study from the National Institutes of Health has found COVID-19 can spread within days from the airways to almost every organ system in the body and can persist there for months.

CBSMiami.com Team