Fox News medical contributor Dr. Marc Siegel argues there should be vaccine incentives, not mandates.

Oregon Gov. Kate Brown, a Democrat, was spotted maskless at an event in Washington, D.C., despite pushing for mask mandates in her own state.

Brown was a "featured guest" at the LGBTQ Victory Fund’s 30th anniversary gala in D.C. and was caught without a face covering in a photo published by an attendee on Twitter.

The Oregon governor’s appearance at the gala coincides with a push for a "permanent" indoor mask mandate in the state.

Brown’s maskless gallivanting illustrates an apparent dissonance with her own state policies.

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At least 17 states now have reported cases of the omicron coronavirus variant, according to the Associated Press.

Those states, as of midday Monday, are California, Colorado, Connecticut, Georgia, Hawaii, Louisiana, Maryland, Massachusetts, Minnesota, Missouri, Nebraska, New Jersey, New York, Pennsylvania, Utah, Washington and Wisconsin.

New York City Mayor Bill de Blasio on Monday issued a "preemptive strike," mandating that all private sector employees in the Big Apple be vaccinated against COVID-19 amid the new threat posed by the omicron variant beginning Dec. 27. 

De Blasio, whose term is set to expire in a matter of weeks, broke the news during an interview on MSNBC’s "Morning Joe" Monday morning.

"We’ve got omicron as a new factor, we’ve got the colder weather, which is going to really create additional challenges with the delta variant, we’ve got holiday gatherings," de Blasio said.

"We in NYC have decided to use a preemptive strike to really do something bold to stop the further growth of COVID," de Blasio said.

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Mary Josephine Generoso, a business owner in New York City, reacts to Mayor Bill de Blasio's possible mandate for restaurants and concert venues.

The CDC says starting today, all travelers heading into the U.S., regardless of vaccination status, must present a negative COVID-19 test taken no more than one day before departure.

"Wearing a mask over your nose and mouth is required in indoor areas of public transportation (including airplanes) traveling into, within, or out of the United States and indoors in U.S. transportation hubs (including airports)," it added.

Dr. Makary dispels the myths and facts on the coronavirus vaccine in light of the Omicron, Delta variants on 'Fox News Live'.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, speaks during the daily briefing at the White House in Washington on Dec. 1. (AP/Susan Walsh)

Dr. Anthony Fauci said on CNN Sunday that scientists need more information before drawing conclusions about omicron’s severity -- but reports from South Africa, where it emerged and is becoming the dominant strain, suggest that hospitalization rates have not increased at a high rate.

“Thus far, it does not look like there’s a great degree of severity to it,” Fauci said. “But we have really got to be careful before we make any determinations that it is less severe or it really doesn’t cause any severe illness, comparable to delta.”

Fauci also said the Biden administration is considering lifting travel restrictions against noncitizens entering the United States from several African countries. 

“Hopefully we’ll be able to lift that ban in a quite reasonable period of time,” Fauci said. “We all feel very badly about the hardship that has been put on not only on South Africa but the other African countries.”

The Associated Press contributed to this report.