By CBS3 Staff

PHILADELPHIA (CBS) — New school year, same story as COVID-19 continues to disrupt in-person learning in Philadelphia. After 18 months of waiting to get back into the classroom, another Philadelphia school has closed due to a COVID-19 outbreak.

The Southwark School in South Philadelphia will be closed through Sept. 26. Students will learn virtually until then.

Additionally, the entire 9th grade class at Roxborough High School will be virtual learning until Friday, Sept. 24 due to at least two positive COVID cases. 10th through 12th graders will report to school as normal.

The school district gets direct orders from the city’s health department on when that action is necessary and how it’s determined.

Just three weeks into the school year and five Philadelphia schools have been forced to close due to a COVID-19 outbreak.

Richmond Elementary in Port Richmond is one of the latest schools to pause in-person learning and revert to an all virtual setting.

Philadelphia School District Superintendent Dr. William Hite says the district gets a directive from the Philadelphia Health Department on when to shutter a school due to COVID cases.

Most recently, Emlen Elementary cited eight in-school cases that forced its closure.

“Once they start to look at that information and the case counts then they would make a recommendation to us to either quarantine a group of students or close the whole school,” Hite said.

The city’s health department will flag a school to pause in-person learning when it has identified six cases within a 14-day incubation period within the school setting, meaning all cases are only linked to in-school transmission.

Schools are using layers of safety protocols to keep outbreaks at bay.

Mastery Charter School has been open for in-person learning since February and was one of the first schools in Philadelphia to implement consistent testing.

“We are doing free weekly testing for students who consent, for all staff who are unvaccinated at this point, and then for any staff who are vaccinated but choose to participate through a federal program called Operation Expanded Testing,” Laura Clancy said.

Mastery Charter identified 43 positive cases within the first two weeks of school, out of 12,000 students in its student body. No closure has ever been necessary.

Meantime, all Philadelphia district schools are conducting weekly testing now. School officials know how critical it is to identify COVID cases early and stop the spread.

“It just gives us critical information and it gives families critical information, especially given the fact that so many infections are asymptomatic,” Clancy said.

The effort to vaccinate as many students and staff within Philadelphia schools is ongoing.

The Black Doctors COVID-19 Consortium hosted a question and answer session Thursday for Philly school staff about keeping students safe. All Philadelphia school teachers and staff must be vaccinated by Sept. 30.

CBS3’s Natasha Brown contributed to this report.