Updated quarantine rules take effect today for middle schoolers in Miami-Dade. From now on, middle school students will be allowed to return to school with a negative PCR test on or after the 5th day following exposure, instead of the previous 10-day requirement. Superintendent Alberto Carvalho says high Schoolers are already under this protocol, and he's hoping to have elementary and k-through-8 students under the same guidelines by week's end. He says there is proof their COVID protocols are working as conditions continue improving. The county is at a 3.7-percent positivity rate, back it August it hit a high of 12.8-percent.