Students are used to getting snow days in Chicago, but kids got the day off on Friday as part of a mass vaccination campaign.

At least 20 schools served as vaccination sites, as city officials called on residents to use the opportunity to get themselves and their children vaccinated and get booster doses if they’re eligible. City employees were also given two hours of paid leave Friday for vaccinations.

“This vaccine is easily available to children and adults now, right now,” Chicago Mayor Lori Lightfoot said during a press briefing Friday morning, before she got her own booster shot. “Invest in the safety of our residents, regardless of their age, as an investment in our here, our now and our future. And it puts us one step closer to putting this pandemic behind us once and for all. The vaccine is the answer.”

The vaccination effort comes just over a week after children ages 5 to 11 became eligible for Pfizer’s COVID-19 vaccine. The first full week of vaccinations has gone “beautifully,” with no side effects reported except for a few sore arms, Dr. Allison Arwady, Chicago’s public health commissioner, said during Friday’s briefing.

She noted that students who are vaccinated do not need to quarantine, as long as they are asymptomatic, if there is a COVID-19 case in their school.

“The No. 1 reason we vaccinate is to protect children, adults, families and get us past COVID,” she said. “Given that we’re trying to also have school in-person and safe as much as we’re able to, another reason to do this is to keep kids in school where COVID protocols remain strong, but vaccine is more important than anything.”

Data from Chicago Public Schools, the third-largest school district in the U.S. with over 330,000 students, shows that over 5,000 students are currently in isolation or quarantine due to COVID-19.

In another incentive, families can receive a $100 gift card if a student gets vaccinated at a Chicago Public Schools event.

City officials stressed the importance of getting vaccinated ahead of the holidays and as COVID-19 cases increase in the city. Nearly 70% of eligible Chicago residents have gotten at least one dose of the vaccine, according to city data. City employees are required to be fully vaccinated by Dec. 31 under a mandate that has faced several court challenges.

“We’re in a very different place this year because of the vaccine. So still be cautious, but make sure that you are fully vaccinated and the people who are gathering around your table are as well,” Lightfoot said.

The city should have more information next week on how the vaccination efforts went Friday, according to Chicago Public Schools CEO Pedro Martinez.

“We’re seeing a very healthy turnout for families,” he said during the briefing. “I can’t emphasize enough to our families, this is an investment for the rest of the school year.”

He said there has been “everything from nervousness to excitement” among young students about the vaccine “because they know they’re going to be able to do more things.”

Jeff Fernando was among those who took the opportunity to get his 5-year-old daughter her first dose Friday.

“Been waiting for it for a long time,” Fernando told Chicago ABC station WLS. “I get paranoid with her in school and I know they take measures but you never know. So I was just happy.”

The Chicago Teachers Union, which held its own vaccination drive Friday, applauded the decision to close schools, saying in a statement it was a “welcome relief from the stress of trying to protect and educate students without the resources to address their needs.” Though the union has also called on the city to broaden vaccine outreach to students, especially those in South Side communities.

Four high schools are serving as vaccination hubs, with free vaccines offered on alternating days.

Schools have been serving as vaccination sites since high school students became eligible to get the shot, seen as trusting and convenient destinations for families in addition to pediatrician offices and other locations.

In Elgin, a suburb outside Chicago, the school district’s 40 elementary schools are holding vaccine clinics throughout the month.

This week, over 1,000 public schools in New York City — the nation’s largest school system — served as vaccination sites for children ages 5 to 11.