Fauci now says you should be masked around all people unless you are certain they have been vaccinated — and adults should get 'boosted' ahead of Thanksgiving celebrations

Dr. Anthony Fauci, infectious diseases expert and head of the National Institute of Allergy and Infectious Diseases, now says that people should remain masked in all indoor settings unless they are confident that the people around them have been fully vaccinated.

Fauci also advised people eligible for a COVID-19 vaccine booster shot to get one before holiday celebrations.

What are the details?

During Thursday's MSNBC broadcast of "All In with Chris Hayes," Fauci said that Americans should remain masked unless they know for sure that people they are around have been fully vaccinated.

Host Chris Hayes asked Fauci what his advice might be ahead of the Thanksgiving holiday.

“In terms of people gathering and the sort of colder weather, which is coming, and we're seeing cases go up," Hayes said. "I keep telling everyone I know this, like, prepare yourself. There will be cases going up this winter. If people are going to get together for gatherings like Thanksgiving, how should they be thinking about it? My instinct is, you know, everyone should be vaccinated, and you should get boosted if you can. Maybe test the day of. How do you think about it?"

In response, Fauci said that as long as all people in the family are vaccinated, Thanksgiving ought to be a safe and enjoyable time.

Fauci warned, however, that if there are any questions about a person's vaccination status, people ought to remain masked out of an abundance of caution.

"The situation is — and let's just take a scenario, you have a family setting. You're vaccinated. Your family members are vaccinated, and even if the children who are yet too young to get vaccinated, go have an enjoyable Thanksgiving in your home," he explained. "You don't need to wear a mask. The situation is that when you are outside in indoor congregant settings where you do not know the vaccine status of people, then you should be wearing a mask. If you're in a situation where everybody is vaccinated, then you really don't need to wear a mask. If you're at home, that's the situation. That's the reason why the CDC says when you're in congregant settings, and you have no idea who's around you, there's no requirement for vaccination. That's when you need to wear a mask. If you know people are vaccinated, you don't need to wear a mask."

He added that despite reports and studies intimating that masks do not prevent the spread of COVID-19, "masks work."

“Anybody who starts saying you shouldn't be wearing a mask because we don't know if masks work, that's been put to bed," the infectious diseases expert insisted. "Masks work, period. There are many studies that now show that. Just like the recent study that has come out from the British study, just literally today it came out."

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