Denver has a strict vaccine mandate for teachers, plus masks. It's keeping kids in school.

DENVER – When fall classes started last week, Principal Cori Herbst-Loehr felt confident.

The school district had not tallied which staff members were vaccinated against COVID-19, in accordance with the mandate for city and county workers. But at her school, Denver Montessori Junior/Senior High, she estimated it was "probably 99.9%."

"I think it's going to help us stay in class," said Sole Gurule Castro, a senior at the school.

By next week, just about all U.S. schools will be back in session, predominantly in person. But Denver Public Schools stands apart. Its teachers were among the first nationwide to be subject to a full vaccine mandate – with no option to be tested frequently instead. The district always planned to require masks come fall, even when the virus was receding in June, before the delta variant surge.

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As of the end of July, 42% of Colorado children ages 12-17 were fully vaccinated, compared with 32% of adolescents nationwide, according to a Centers for Disease Control and Prevention study. About 72% of Denver County residents 12 years and older are fully vaccinated, compared with the national average of 61.5%. Officials credit consistent messaging among schools, politicians and health care officials with boosting vaccination rates.

The efforts in Denver have worked. After about 90,000 students and 15,000 staff returned to school buildings, infections remained comparatively low nearly two weeks later. In all, 34 staffers and 85 students tested positive for the coronavirus as of Sept. 2, according to district data, and 117 students were quarantined.

The strict orders are not without controversy. Some middle and high school students in Denver walked out of classes this week to protest wearing masks in school, according to news reports.

Denver's outlook two weeks into school is remarkable compared with quarantined students in the thousands at comparably sized districts around the country – where staff have not been subject to full vaccine mandates.

In Atlanta, Fulton County Schools reported 1,022 positive cases after the first week of classes, according to WSB-TV. The district initially exempted 15 schools from wearing masks, then required masking after cases rose, the Atlanta Journal-Constitution reported. There's no vaccine mandate for staff.

In Louisville, Kentucky, Jefferson County Schools reported 485 positive student cases a week and a half after reopening, even though masks were required. The district does not mandate vaccines for staff. In total, 2,282 students were sent home to quarantine, according to the Louisville Courier-Journal.

In Texas, the Austin School District opened with a mask mandate for its more than 70,000 students Aug. 17. It reported 189 positive student cases and 30 staff cases after its first week, according to district data. The district offers teachers a $250 incentive to get vaccinated, but it will probably mandate vaccines after Oct. 15, according to KVUE News.

Vaccination rates in the Atlanta and Louisville areas and in Texas are all lower than in Denver, according to CDC data. In Atlanta, the percentage of fully vaccinated children ages 12 and older is less than half that in Denver.

"We are not going to face-cover our way out of this pandemic," said Bob McDonald, executive director of Denver's Department of Public Health and Environment. "The only way to get there is to mandate vaccines."

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Vaccines maximize class time

Some of the cooperation among leaders in Denver is due to political alignment. The city is solidly Democratic, and Democrats tend to embrace vaccines and vaccine mandates more readily than Republicans, polling shows. Fights over masks have been more prevalent in some of the Republican-leaning suburbs outside Denver.

The full COVID-19 vaccine mandate for Denver's school, city and county workers, announced by the mayor on Aug. 2, came as other leaders nationwide tiptoed into less restrictive vaccine orders.

The only way to get around a vaccine mandate as a Denver public worker or a worker in a high-risk environment is a medical or religious exemption. Signing up for regular coronavirus tests won't exempt workers, nor will personal opposition to vaccines.

Last month, the Food and Drug Administration fully approved the Pfizer vaccine, prompting more public and private employers to order employees to get vaccinated or face potential termination.

McDonald, who has spent nearly 30 years working for Denver in a public health capacity, recommended a full mandate for the city.

He diplomatically refers to "less than civil" emails he's received, but he's had to move homes because of personal threats.

He said vaccines are critical not only for public health and for ending the pandemic but also to maximize class time for children who should stay in school for their academic and emotional development.

McDonald and district leaders battled resistance by spreading consistent messaging about the safety of vaccines. During an hourlong telephone town hall for staff held by the district Aug. 16, attended by more than 6,000 people, McDonald methodically answered questions from skeptical teachers and parents.

Another steady voice: Steven Federico, director of pediatrics at Denver Health, which runs community clinics in 19 schools. The health care system is the primary care provider for the majority of district children, Federico said.

“We’ve been trying to maximize the number of in-person learning days to make up for last year and to support the kids," Federico said. "We've all been clear in that goal. The way you do that is vaccinate as many people as possible and mask.”

Delta variant infections threaten class time

Pediatric COVID-19 cases have risen as the more infectious delta variant has spread, but a relatively low number of children get very sick. Severe illness in kids is rare, but children of color are more likely to be affected.

For many, the bigger threat is the potential disruption to in-person learning that best nurtures academic, social and emotional growth.

Across the country, thousands of otherwise healthy children are sent home to quarantine because of exposure to positive cases in schools. For those who face other disadvantages, that will further hinder their ability to make up missed academics and social connections.

Many districts did not prepare to continue remote learning this year, which means some students get no schooling at all during their quarantines. In Tennessee, some districts don't offer instruction to students in quarantine, while others use inclement weather days for full-school closures.

To avoid that fate, Denver pushed hard for eligible students to get vaccinated. It established vaccine sites at schools in spring – before classes let out for the summer, Federico said.

“We had to rush," he said. "We knew we had a two- to three-week window to access a lot of kids."

Vaccines at the school-based clinics were offered to everyone, not just students, Federico said. Often, teens convinced their entire families to get vaccinated. The district worked with predominantly Black churches to urge vaccinations.

The city struggles with racial disparities in vaccine adoption. Denver's older Latino populations and younger Black populations are the most resistant, a trend seen nationwide, Federico said.

Among eligible teens who are white, vaccination rates are over 90%, but among teenage Latinos, it's about 50%, and among Black teens it's 37% in Denver, according to the city's Department of Public Health and Environment.

"We haven't unlocked the disparity problem," Federico said. "It continues to be hard work, but I think vaccination in schools is helping in real time."

Opposition from teachers to the vaccine mandate has been limited, said Rob Gould, president of the Denver Classroom Teachers Association union.

In 2019, the Denver teachers strike, he said, strengthened the voice of the union with partners such as the district. Even in the summer when infections went down, talks continued between the district, teachers, city and public health department.

“We saw the rise of the delta variant, and we said, ‘We have to do masks,’” Gould said. “It was a no-brainer.”

Gould said teachers were not consulted before the city announced the vaccine mandate. The union supports vaccines, he said, but it had to work harder to get answers to the inevitable questions that arose about the mandate.

Staff vaccine data to come, testing to continue

Denver school staff and other public workers are required to show proof of vaccination by Sept. 30 or to receive approval for an exemption.

The district encourages coronavirus testing, which has been widely and freely available since last year.

One big partner on that front: COVIDCheck Colorado, an enterprise established by the Gary Community Ventures foundation but fully paid for by the state. The foundation funneled state money into testing sites, including at schools, and partnerships with labs that could process test results swiftly.

"We all have been trying to figure out: How do we get kids back in school?" said Nina Safane, executive director of COVIDCheck Colorado. "We figured out all the logistics to make testing happen, then had financial support for the state. That's what made it all possible."

Paired with high vaccination rates, access to vast, free and reliable testing has been a key mitigation strategy, Safane said, because it allows communities to identify cases quickly.

The district has tracked and posted infection rates by school, and reviews cases to try to determine the infection location, as well as close contacts.

By the end of the second week of school, Denver Montessori Junior/High was still free of infections.

Amir Hall, a senior, said it was a welcome change from the previous school year. At that time, he said, some students came to school only a couple of days a week. He wasn't a fan of remote learning, he said, and wearing masks in class isn't a big deal.

"I'd rather come," he said.

Contributing: Olivia Krauth, Louisville Courier-Journal; Meghan Mangrum, Nashville Tennessean

Contact Erin Richards at (414) 207-3145 or erin.richards@usatoday.com. Follow her on Twitter at @emrichards.

This article originally appeared on USA TODAY: Teacher COVID vaccine mandate, masks stop quarantine in Denver schools