Math teacher Michelle Higby works behind a shield at her desk as a precaution because she is immunocompromised and has a mother receiving cancer treatment. (Harika Maddala/Bay City News)

Hundreds of San Francisco Unified School District teachers and aides have been out of school this week amid a surge in COVID-19 cases as classes resume after the winter break, and the district says it is ramping up testing for the virus after receiving a shipment of rapid tests.

There were 693 requests for substitutes Wednesday at schools across the district, with many district staff members credentialed as teachers but not currently assigned a class filling in for some of them, SFUSD spokeswoman Laura Dudnick said.

United Educators of San Francisco, the teachers’ union for SFUSD, on Wednesday criticized the district’s response to the recent surge in COVID cases, saying SFUSD did not develop an adequate plan and did not require students and staff to show a negative test result before returning to campus, as some other districts have done.

District Superintendent Vincent Matthews issued a statement Wednesday saying SFUSD “encouraged testing, set up new testing sites and sent out information about numerous ways to get tested prior to school reopening. Throughout this week and this weekend we are making rapid testing available at several schools and district headquarters.”

The district received a shipment of rapid tests late Tuesday from the state and is preparing them for distribution and delivery to school sites, according to Matthews.

UESF president Cassondra Curiel said the union and the city’s Labor Council would work to get the tests distributed throughout the district’s schools.

“There have been serious gaps in judgment. But we can all turn it around so that we can give our students the opportunity for a smooth school year,” Curiel said in a statement. “UESF and our labor colleagues are offering to do our part. We hope SFUSD and the city can step up to the challenge.”

Matthews said, “We appreciate any offers to help — all of our staff and families will need to be a part of helping students to receive and administer the self-test kits.”

The superintendent said SFUSD has also been distributing personal protective equipment regularly to schools to keep staff and students safe.

“We know this is a challenging time for the community. Our staff and families have done a great job at following public health protocols and we plan to continue to follow guidance from public health experts,” Matthews said. “This surge, while intense, is expected to be relatively brief and omicron by all reports is more mild than other previous variants. We will get through this surge by continuing to get vaccinated, masking, staying home when sick, and testing.”

More information from SFUSD about COVID-19 testing options can be found at https://www.sfusd.edu/covid-19-response-updates-and-resources/covid-19-surveillance-testing-students/covid-19-testing-locations-and-dates.