The report that the CDC released late last week pertaining to a May COVID outbreak at a Marin County school continues to have a ripple effect nationwide — showing how classrooms, even with windows open and kids masked, can be vulnerable to the Delta variant.

The school involved has now been identified as the private, Catholic elementary school Our Lady of Loretto School in Novato, as Bay Area News Group reports, though it is not identified by name in the CDC report. Marin County Public Health Officer Dr. Matt Willis, who co-authored the report, has now produced a video discussing it, and he says that the school "was an excellent partner" in the process of creating the report and was "immediately responsive" to the health department's inquiries.

"If anything, we see this response effort as a success in demonstrating school and public health partnership," Willis says.

Also, Willis cautions that fingers shouldn't be pointed at the school or the unvaccinated teacher who was found to be the "index case" in the outbreak.

"It’s a mistake here to focus on individual blame,” says Willis. “In fact, the message is the opposite — it’s about building systems and policies that protect schools and prevent outbreaks.”

"Everyone makes mistakes," Willis adds. “But with Delta, we don’t have a very wide margin for errors."

Willis highlights how this outbreak remained isolated to the school and several parents and did not spread wider, thanks to high rates of vaccination in the county by late May. And this occurred at a time when over 30,000 students were back in classrooms full-time, at 116 public and private schools across the county.

Not only does the case study of this outbreak hold lessons about classroom safety — namely that an air filter and open windows are no match for Delta, given that the teacher was occasionally unmasked while reading aloud — it also was an early example of how the variant impacts kids, and how it causes breakthrough infections in adults.

Dr. Lisa Santora, the county's deputy health officer and another co-author of the report, calls it a "canary in coal mine scenario" that signaled to the county that mask-wearing was going to be continually vital to stopping virus spread.

And Mary Jane Burke, the county's superintendent of schools, tells Bay Area News Group, "It was the first time we saw the Delta variant have an impact on children in the county — maybe even the country."

In the May outbreak, 12 out of 24 students in the classroom of an infected teacher became COVID-positive, including all five students in the front row, closest to the teacher. The outbreak spread to six other students in a different classroom — something that was attributed to a sleepover, we now learn — as well as four siblings of separate students in the original classroom, and three vaccinated parents.

Bay Area News Group also reached out for comment from the Archdiocese of San Francisco, under whose jurisdiction the Novato school falls, and their statement said, "In consultation with the 11 other dioceses of California, the Archdiocese of San Francisco remains committed to following recommended public health guidance for all parishes and schools. Our adherence to these same public safety measures allowed us a successful return to Catholic school campuses last year, welcoming back over 23,000 students. Each school displays their current COVID-19 measures and protocols on their website for students, parents and the school community."