The outbreak, at Our Lady of Loretto School, a private elementary school, is being seen as a U.S. test case for virus mitigation in schools nationwide in a report published Friday by the Centers for Disease Control and Prevention.
"It's a mistake here to focus on individual blame," said Dr. Matt Willis, the Marin public health officer. "In fact, the message is the opposite — it's about building systems and policies that protect schools and prevent outbreaks."
"Everyone makes mistakes," Willis added. "But with delta, we don't have a very wide margin for errors."
The outbreak occurred after an unvaccinated and sometimes unmasked teacher ended up infecting 27 people — many of those children too young for shots. Genetic sequencing identified the virus involved as the highly transmissible and now dominant delta variant, the report said.
The incident led to the largest number of school-related infections in Marin since the start of the pandemic.
"Given this outbreak occurred in May and June, we were able to incorporate our observations in the development of our 32-point plan and the guidance we've offered schools over the summer, preparing for fall," Willis said.
"This study shows us that all of us — students, teachers, staff and parents — must be extra vigilant because letting our guard down can be costly with the delta variant," he said.
School principal Kathleen Kraft declined to respond to requests for comment, as did Pamela Lyons, superintendent of schools for the Archdiocese of San Francisco. However, the 205-student school, like all of 117 Marin schools, has upgraded its 32-point virus safety plan on the Marin County Office of Education website as required.
"The most important message from this story is how critical it is that we continue to adhere to public health guidance on mitigation strategies that have proven so successful to keeping our students and staff safe, " Mary Jane Burke, Marin superintendent of schools, said Monday.
"Get vaccinated. Stay home when you're sick. Wear a mask. Wash your hands," Burke added. "All Marin County school safety guidelines, from the beginning, apply to all Marin County schools — public, independent, private and parochial. As Dr. Willis has said, 'The virus doesn't care.'"
Mary Powers, assistant communications director for the Archdiocese of San Francisco, released a statement Monday saying its school administration "follows CDC guidance, as well as state and local protocols, to ensure the safety and security of our school communities."
"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," the statement said.
"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," the statement said. "Each school displays their current COVID-19 measures and protocols on their website for students, parents and the school community."
According to Willis, the Novato school voluntarily cooperated in the case study.
"The school was an excellent partner in this process, being immediately responsive, staff knew exactly what to do with reporting the case and cooperating with elements of the outbreak investigation," he said. "If anything, we see this response effort as a success in demonstrating school and public health partnership."
In addition to the teacher, students in two classrooms and their family members were infected the report said. All the infected students were under age 12 and too young to be vaccinated.
Only two of the school's teachers were unvaccinated, including the infected teacher. No other staff tested positive. More than half the infected family members were unvaccinated. But three of the parents who got sick were vaccinated. They all came down with fever, chills, cough, headache and loss of smell — well before it became clear how vulnerable the inoculated were to delta.
The infected teacher had attended social events from May 13 to 16 and did not know of any COVID-19 exposure but began feeling fatigue and nasal congestion on May 19, the report said. Believing the symptoms were from allergies, the teacher continued working May 17 to 21 as coughing, headaches and fever set in.
The teacher's classroom had an open door and windows plus an air purifier, and the state at the time required staff and students at schools to wear masks indoors and out. The report found that students adhered to the mask requirement, but that the teacher was reportedly unmasked on occasions when reading aloud in class.
The teacher got tested May 21 and was confirmed positive for COVID-19 two days later, the report said. It found that the teacher had infected half of the 24 students in the classroom, and that eight of those 12 were seated in the two rows closest to the teacher's desk.
In addition, six of 18 students in a separate grade at the school, all too young for vaccination, also tested positive for COVID-19, as did eight family members of the students in those two grades, the report said. Four of those were siblings of the students in the infected teacher's class who attended the school in other grades. The other four were parents, three of whom were fully vaccinated.
It appeared some of the spread among students in the second class was linked to a sleepover.
The report said that although three of the infected students' vaccinated parents also caught the virus, any spread beyond the school likely was limited by the community's high vaccination rates, with about 72 percent of those eligible being fully vaccinated at the time.
All of those infected recovered, and none became severely ill, said county epidemiologist Tracy Lam-Hine, lead author of the study.
But Marin health officials felt that their findings about the outbreak were important to share nationally as kids return to campuses this month for the new school year. For many in California, it's their first full-time, in-person instruction since March 2020, and it comes amid community outbreaks of the delta variant.
Dr. Lisa Santora, Marin County's deputy health officer, said the "breakthrough infections" of vaccinated parents at a time when the delta variant was not yet dominant and spreading rapidly across the country "was a canary in coal mine scenario for us" signaling the continued need for face masks and other protections.
"This showed our vulnerability, even as a highly vaccinated community, to the delta variant," Santora said.
Prior to the Novato school outbreak, Burke said, " Marin County schools had provided about 2.7 million in-person student days with only 12 cases of in-school transmission — and zero student to adult transmissions — which jumped to 19 suspected in-school transmissions from this one event."
"It was the first time we saw the delta variant have an impact on children in the county — maybe even the country," Burke added. "It punctuates the importance of our efforts in strictly following Marin County public health guidance."
Willis said although the teacher had symptoms and came to work anyway, it was before officials or the public had had any experience with the delta variant. In May and June, Marin was moving toward the yellow tier of looser virus restrictions under the state's former color-coded virus status tracking system.
"How many of us have woke up feeling 'off' and attributed symptoms to allergies or feeling run down and chose to run errands or go to work anyway?" Willis said. "How many of us have, in our workplaces, chosen to remove our masks for a couple of minutes because you thought, 'Just a couple of minutes should be okay'?"
Willis, Santora and Burke are expected to address Marin schools' coronavirus status during a webinar at 1 p.m. Sept. 14. Access information is at marinschools.org.
©2021 The Marin Independent Journal (Novato, Calif.). Distributed by Tribune Content Agency, LLC.
