By Kristina Rex

BOSTON (CBS) — A young crowd of thousands in their teens and early twenties, draped in feather boas and 1970s-era bell-bottoms, flocked to the TD Garden Monday night for the Harry Styles “Love on Tour” concert.

The concert had been sold out for months, and resale prices only were as high as $2,700 per ticket the night of the show.

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Hanging from the fans’ necks? Not VIP lanyards, but their vaccine cards.

In order to enter the TD Garden for any event, fans need either proof of vaccination or a negative COVID-19 test. All fans must wear masks inside regardless of vaccine status.

“Big crowds make me kind of anxious but having my vaccine, it’s like OK, I know I’ll be safer than a person who doesn’t have the vaccine,” one fan told WBZ.

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Unlike Bruins games or the Eagles concert from over the summer, hundreds of concertgoers from Harry Styles weren’t yet at the vaccine-eligible age, and instead had to get a negative COVID test to see their first-ever concert.

Tufts Medical Center epidemiologist Dr. Shira Doron explained the risks of a crowded indoor event with many unvaccinated people.

“People who are too young to be vaccinated are also protected by their youth, so could the concert be a super spreader event? It could. Could there be transmission in an indoor setting with a lot of people close to each other? There could. But I think everyone in this day and age knows that risk,” she said. “Ensuring that a large portion of that population is vaccinated brings the risk of someone getting infected way down.”

Dr. Doron explained that wearing masks, as well as the overall trend of fewer hospitalizations, make an event like the concert less of a risk.

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An independent FDA vaccine panel is considering expanding Pfizer’s vaccine to cover kids ages 5 to 11 in a discussion on Tuesday, which could pave the way for the vaccine’s approval in younger age groups following a Pfizer study that showed high efficacy in kids.

Kristina Rex