By Marissa Perlman

EL DORADO HILLS (CBS13) – Hundreds of Oak Ridge High School students in El Dorado Hills were told to stay home due to an uptick in positive COVID-19 cases that may be months old.

A letter was sent home to parents this week. Some were frustrated saying their kids were being told they can’t go to school.

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“Telling 200 kids they can’t go to school for two weeks, that doesn’t seem like a good solution,” said parent Rob Grupp.

He says his daughter Isabelle was told to quarantine.

This time, it’s because athletes are being tested weekly for sports. The school said it is increasing “asymptomatic surveillance” testing.

“That’s not good,” said Grupp.

At Oak Ridge High School there are 19 active student COVID-19 cases, but 215 students are in quarantine. That’s more than 10% of the student population.

Everyone the district says was exposed is required to stay home for two weeks no matter what, even with a negative test.

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“It’s dumb because it’s negative, you aren’t going to give it to anyone, and you get behind on homework and everything,” said one student.

The district says athletes are tested using a PCR COVID test, which can’t distinguish between an active case or a case from months ago.

Parts of the RNA or the genetic information of the virus can show up on those tests after the student is no longer contagious. Infectious disease experts say it’s not necessary to quarantine.

“If you have a child with a known infection from an RNA test that was documented in the past three months, they don’t need to be isolated,” said Dr. Phillip Norris.

Parents say, before keeping kids at home, the system should be checked.

“Before they go quarantine 10 percent of the school they should probably do a second test on that student to see if it’s a current case or not,” said Grupp.

The latest numbers from the district show there are more than 400 students districtwide now in quarantine.

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District Spokesperson Serena Fuson said in a statement:

“We have seen a recent increase in the number of students who have tested positive for COVID-19 since we have increased our asymptomatic surveillance testing for athletic participation. We are concerned that many of the asymptomatic cases are due to exposure that has happened in the previous weeks and months as many students do not have any symptoms. The PCR tests are unable to distinguish between an active case and one that took place months ago.”