2 Vaccinated People Sickened In COVID Outbreak At Montco School

MONTGOMERY COUNTY, PA — Eight students and two fully vaccinated family members have contracted the coronavirus stemming from an outbreak at a Montgomery County elementary school, officials confirmed Monday.

Authorities have noted in the past that transmission among young students, as well as cases among the fully vaccinated, are both extremely rare.

A variant strain of the virus could be responsible for the outbreak, which occurred in a second grade class at Penn Valley Elementary School in the Lower Merion School District. The district said the class has been quarantined since Friday and that no other cases have occurred elsewhere in the school.

Authorities identified two potential factors in the spread: reduced airflow in the room and the growing presence of more-contagious variants of the COVID-19 virus in the community.

School officials "cannot say definitively whether the diminished fresh airflow contributed to the outbreak; however, it could be a factor," they noted. The county's Office of Public of Health is also investigating and "noted the possibility of a variant strain of COVID-19 being a factor, citing both the rapid spread within the class and the fact that two vaccinated family members of impacted students have also tested positive."

Statistics on vaccine efficacy in Pennsylvania indicate the situation is extremely rare. A tiny fraction of fully vaccinated Pennsylvanians — 331 out of 2.6 million — have contracted the virus as of last week. That's a 99.9 success rate, higher even than the clinical trials of the Pfizer and Moderna vaccines forecast.

It is not known which vaccine the Penn Valley family members received.

Some small number of cases among vaccinated persons was expected, as Moderna's clinical efficacy rate was 94 percent and Pfizer's was 95 percent (the recently paused Johnson & Johnson vaccine was 72 percent). These numbers are particularly high, as the seasonal flu vaccine is often only about 40 percent effective, officials said.

The virus variant first detected in the United Kingdom, known as B.1.1.7, is believed to be about 1.5 times more contagious. It's still uncertain how well vaccines protect against the variants. A total of 186 variant cases have been confirmed in the county, though testing for variants is very difficult and it's believed that this is but a small percentage of the total number of cases.

School officials noted that only about 30 percent of the maximum amount of fresh air was coming into the classroom, due to an issue with a piece of equipment in the HVAC system. A manual damper in the ceiling's ductwork was closed too far.

"Breakthrough cases are normal with any vaccine," Maggi Barton, a spokesperson for the Pennsylvania Department of Health, told Patch. "We know that the more people are vaccinated, and the fewer chances for exposure and infection there are, the less likely we are to see breakthrough cases."

Officials also say that even in the case of rare infection among the fully vaccinated, that the vaccine is highly effective at preventing serious illness or hospitalization due to the virus.

Lower Merion says its HVAC system "met or exceeded standards" even before the pandemic, and school operations staff will keep running air quality assurance tests in all buildings in the coming weeks. The district and Montgomery County's Office of Public Health are continuing to investigate.

With reporting from Patch correspondent Max Bennett