COVID cases in Montgomery County Public Schools are spiking, reaching their highest levels since the January omicron wave.

More than 2,910 cases have been reported amongst students and staff in the past 10 days, according to MCPS data. So far in May, 12,027 students have quarantined — the second-highest number of quarantined students recorded this academic year, behind the January total of 15,191.

The surge has prompted one school, Sherwood Elementary School, to reinstate its mask requirement after more than 63 students and staff tested positive in recent days — making up over 11% of the school’s population. It’s the highest percentage of COVID cases of any school in the system. MCPS had lifted its mask mandate back in March.

According to the Bethesda Beat, MCPS alerted parents and families last week that classrooms with three or more positive cases in the past 10 days may be asked to resume masking.

The spike in the county’s schools likely mirrors a wave occurring in the county, which might be harder to see just from looking at publicly available COVID data. Unlike the school system, which maintains a dashboard of daily case counts, Montgomery County, along with nearly all other local jurisdictions, has done away with reporting daily numbers and instead reports case rates and trends over time. The proliferation of at-home rapid tests also means that some cases likely go unreported, making the data we do have a probable undercount.  The Centers for Disease Control and Prevention lists Montgomery County in the “medium” zone of virus transmission — a measure that is determined by the case rate per 100,000 residents, new COVID admissions to the hospital, and the percentage of beds occupied. As of Monday, the county’s case rate per 100,000 residents was nearly 320 — a 47% increase over the previous seven days.

In a newsletter to community members on Tuesday, Montgomery County Executive Marc Elrich urged residents to resume masking in public spaces and test frequently after returning from gatherings and travel, but stopped short of reinstating any mandates.

“While there has not been a commensurate increase in COVID-19 hospitalizations in the county, there is concern about the impact that spring break travel and holiday gatherings may have on transmission,” Elrich wrote.

Viral transmission in schools is also driving cases up in Northern Virginia, where most jurisdictions are in the “medium” zone of transmission. On Monday, Fairfax County Public Schools reported its highest-ever number of cases amongst students and staff. So far this month, the system has reported 4,791 case amongst students and staff — well beyond the 3,559 reported in January.