Stamford school officials say after performing contact tracing, it was safe to keep school buildings open despite positive COVID-19 tests at Westhill High School, Stamford High School and Rippowam Middle School.

Liz Levy, whose children attend Westhill, says the building's HVAC system has been upgraded but not to the MERV-13 air filters recommended by the Centers for Disease Control and Prevention for protecting from coronavirus.

The school underwent heavy remediation last year after accumulating mold began to cause health problems for teachers and students.

Levy says the school's repaired HVAC only uses MERV-8 filters.

Stamford Superintendent Tamu Lucero says the repaired system was given by the state Department of Public Health. Infectious disease experts say positive tests are no cause for panic.

Dr. Manisha Juthani says the number of cases in the state is still low enough to stop infections before they spread.