CHICAGO (CBS) — More cases of the omicron variant of the novel coronavirus have been confirmed in the U.S. – and travel restrictions are starting to take effect as the variant spreads.

As CBS 2 Political Investigator Dana Kozlov reported Thursday night, President Joe Biden said he does not think shutdowns or lockdowns are necessary right now. But traveling this holiday season will require tougher testing.

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The omicron variant is making its way across the United States as expected. In New York state, officials said five cases have now been confirmed. Other cases have been found within the past day in Minnesota, Colorado, and California.

“It’s probably already more widely spread than our early determinations have indicated, and it will spread further,” said infectious diseases expert Dr. William Schaffner.

The rise in delta variant cases, and the new U.S. omicron cases, prompted President Biden to announce tougher travel restrictions and other efforts to fight the spread. In addition to banning travelers form eight countries in southern Africa from entering the U.S. effective Monday, Dec. 6 – as announced last week – the president is now requiring travelers coming back into the United States to take a COVID-19 test within one day of their entry.

Meanwhile, the mask mandate on all planes, trains, and other public transportation nationwide has been extended through March.

President Biden is also requiring private insurance to reimburse people for at-home COVID testing kits.

“Experts say that COVID-19 cases will continue to rise in the weeks ahead and this winter, so we need to be ready,” said President Biden.

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Locally, Cook County Public Health senior medical officer Dr. Rachel Rubin said the county is on notice.

“We’re much more worried about delta than we are about omicron,” Rubin said, “but like your first question indicated, we are certainly on high alert – and we’re watching this very carefully.”

Rubin believes the COVID-19 vaccine will still be effective against the new variant when it comes to preventing severe illness and death.

So far, there have been no confirmed cases of the omicron variant in Illinois – yet.

“If omicron continues to rise and begins to represent a higher proportion of the cases that we’re seeing, is that we’ll see more breakthrough cases,” Rubin said.

Dr. Rubin not only stressed the importance of getting the COVID vaccine, but also said people should not wait to get their booster, if eligible.

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Neither Gov. JB Pritzker nor Mayor Lori Lightfoot have indicated they are looking at any shutdowns either.