An Atlanta charter school will quarantine more than 100 students after two students and two employees tested positive for COVID-19 in the first week of classes.

Drew Charter School started the school year Tuesday with more than 90% of its nearly 2,000 students learning in-person.

By Thursday, students identified as having close contact with those who tested positive began to quarantine. Head of School Peter McKnight said students impacted are primarily in grades 2, 6 and 7.

“As best we can tell, none of the cases have been linked on campus. We are still investigating that,” he said.

Because a “significant number” of eighth grade teachers also are in quarantine, students in the eighth grade class are learning virtually until Aug. 10, he said.

COVID-19 safety protocols at Drew go beyond what many other schools are doing. Everyone must wear masks. Staff must be tested weekly for the coronavirus. Students are “strongly encouraged” to participate in the testing program.

In the days leading up to the first day of school, Drew tested more than 1,900 students and staff. That resulted in catching three additional positive cases among students before they entered campus, and two more staff cases.

Jessica Seares’ daughter is among the sixth graders now quarantining. Seares called the Drew situation a “test case” as more schools reopen in the coming days.

“I felt like this was going to happen, I just didn’t think it was going to happen this fast,” she said.

Her daughter, age 10, is not old enough to be vaccinated. She was already dressed in her uniform when Seares had to tell her that she couldn’t go to school.

“She was very sad that she couldn’t go back. It was hard to break the news to her,” she said.

McKnight said none of the four staff members who tested positive in the days before and right after school started were vaccinated. Vaccines are not mandatory for employees, though about three quarters have received the shots.

About a third of vaccine-eligible Drew students are vaccinated. Vaccines are not yet available to children under 12.

McKnight said the school is urging more students to get the shots.

”Vaccinations are hands down our best strategy to protect … health and safety,” he said.

Seares said she thinks all students should be required to take regular COVID-19 tests to reduce the spread.

“It’s just exhausting, and I am concerned about the fact that the measures that were in place were not even enough,” she said.

Unvaccinated students will be quarantined for 14 calendar days, McKnight said. Vaccinated students can return after five days if they have a negative test.

Drew is part of Atlanta Public Schools, whose district-run schools will open Aug. 5.

This story has been updated.