The district is encouraging everyone gets tested for COVID-19 after winter break.
It's all in hopes of slowing the spread of the omicron variant and keeping students and teachers healthy. In Harris County, there are almost 65,000 active cases.
Sunday, HISD opened two COVID-19 testing sites in hopes that students and staff would get tested.
The line was long at the Bellaire High School location.
READ MORE: HISD families and staff line up for free COVID-19 testing
All students and staff, no matter vaccination status, are being encouraged by the district to get tested for COVID.
The quarantine time for students who test positive is different from the new guidelines for adults.
The CDC is recommending that children isolate for 10 days, and 24 hours must pass after a child has had a fever before they can return to school.
For adults, isolation is encouraged for five days, then five more days of wearing a mask if the adult has no COVID symptoms, but did test positive.
ABC13 caught up with a teacher who was waiting in the long line Sunday.
"You are going to wait a long time if you go to a Walgreens or Next Level or whatever," Corina Olguin said. "At least we're jamming to music and just hanging out in the car for a little bit."
The Houston Health Department Delmar Stadium testing location is offering free tests by appointment only.
As of Monday morning, the next available time slots were on Wednesday morning.
Visit curative.com to make an appointment.
SEE ALSO: COVID testing will be available for students and staff at all HISD campuses in 2022