MIAMI (CBSMiami) – Students at MAST Academy went back to class Tuesday morning, one day after being forced to return to virtual learning only after two students contracted COVID-19.

Miami-Dade County Public Schools Superintendent Alberto Carvalho said the marine magnet school on Virginia Key was thoroughly sanitized ahead of Tuesday’s reopening and urged those in close contact with the two students to stay home.

“If children are exhibiting symptoms do not send them to school to infect the school community,” said Carvalho on Monday.

Some students were concerned about the reopening.

“I feel they open too fast and closed it too fast. It’s just weird,” said a student named Olivia.

Some parents say they were not worried about their children’s safety.

“I feel comfortable. I feel they are safe. I am glad they closed the school and they reopened and they did everything just to be careful,” said one parent.

Another agreed.

“I just dropped off my 10th grader. The school has taken all measures to make it safe yesterday so we all came back today. My daughter got tested and she came back negative and we believe there are only 2 isolated cases.”

Karla Hernandez-Mats, the President of the United Teachers of Dade, heard the two students w ho contracted the coronavirus had been at a party on Key Biscayne.

“We have heard these students were at a party which is a spreading center, a spreading event,” she said on Monday.

Carvalho says Miami-Dade Schools worked closely with the state health department.

“If any children exhibit symptoms, they should stay home and inform the school community and contact the school’s emergency hotline at 305 995-1550.”

As of Tuesday morning, there are 12 confirmed cases in Miami-Dade County Public Schools. Eleven students and one employee according to the Miami-Dade County Public Schools COVID-19 dashboard, since schools started reopening on Oct. 5.

There are 2 cases at Coral Park Elementary, which did not shutdown and 2 at MAST Academy. There is one each at Bowman Ashe/Doolin K-8 Academy, Charles D. Wyche Elementary, Flagami Elementary, North Dade Center of Modern Language Arts, Poinciana Park Elementary, Royal Green Elementary, William H. Lehman Elementary and Zora N. Hurston Elementary.

Other reported cases not on the dashboard include one at Eugenia B. Thomas K-8, and one at Downtown Doral Charter School.

The United Teachers of Dade says there are cases at 15 schools.

Superintendent Carvalho explained the delay in reporting positive cases to the Miami-Dade County Schools COVID-19 dashboard.

“The dashboard is not updated until the Department of Health confirms. They are the only entity that can certify the positive cases documented so there will always be a lag in the number of days or hours that cases come to us.”

The United Teachers of Dade wants to remind students about the importance of masks.

“Our kids need to keep wearing a mask and continue washing their hands and try to keep 6 feet of social distancing though I realize that may not be easy as they have not seen each other for some time,” said Hernandez-Mats.

Broward County schools also had its first COVID-19 case since students started in person classes.

A first grader from Pembroke Pines Charter School West Campus.

A spokesperson told CBS4 News parents were notified and the school is following Broward school district protocols for handling COVID-19 cases.

There are two employee cases being reported by The Sun Sentinel which says those cases are at Miramar High and Park Trail Elementary in Parkland. In addition, the paper reports four students have been sent home due to possible coronavirus symptoms at Central Park Elementary in Plantation and Palm Cove, Chapel Trail and Pembroke Pines Elementary schools in Pembroke Pines.

Broward schools started its staggered reopening on Friday with the return of kids in Pre-K to 2 and special needs students. Students in grades 3, 4, 5, 6 and 9 returned Tuesday while those in grades 7, 8, 10, 11 and 12 can return Thursday.