Even as they recommended working to reopen schools in-person, the nation’s science academies warned, “It is likely that someone in the school community will contract COVID-19.” 

Largely missing from the reopening protocols at states and schools around the nation are concrete plans for what administrators will do when coronavirus infections enter a school.

The prospect of reopening school in the fall is looking less likely in much of the nation. Confirmed COVID-19 cases in the USA have skyrocketed past 3.7 million, and more than half of states have paused or scaled back efforts to reopen their economies.

A growing number of school districts have decided to start the fall semester online. California’s districts with high cases or transmission must begin the academic year with distance learning, the state’s governor announced Friday. In other states, districts pushed back their start dates.

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Many schools still plan to hold in-person classes. They’re releasing plans that include implementing social distancing, closing school buildings to visitors and, in some cases, splitting students into groups that attend school on some days and study from home on others. 

How a school would handle multiple coronavirus cases across the building, and how many infected students or teachers would raise alarms, are details often left up to parents to guess. Typical plans include only references to “case-by-case” decisions.

USA TODAY Network reporters reviewed 35 schools’ reopening plans. Most plans didn’t include specifics on decisions that would lead to closing school buildings and putting learning online for all students.

Instead, most schools echoed some of the basic recommendations from the Centers for Disease Control and Prevention: deep-cleaning the area where an infected person spent time, quarantining the person, and leaving it up to consultation with state or local health officials to make decisions about school closures.

The CDC recommends dismissing school for at least two to five days after an infected person is in the building, but most school plans don’t reference closing whole buildings. 

The vague plans go against advice from the National Academies of Sciences, Engineering and Medicine, which said clear thresholds should be established before the school year begins about the conditions that would force schools to close again.

One exception is California, where Gov. Gavin Newsom issued guidance Friday that schools must remain remote until their county has been off the state’s “watch list” for 14 days. He laid out in detail when classrooms and schools would have to close if there is an outbreak.

A classroom would have to close and the students and teacher would quarantine for 14 days if any of them tested positive for the virus. If the school reports multiple cases, or 5% of students and staff test positive within this 14-day period, the entire school should revert to distance learning.

In Miami-Dade County, Florida, the fourth-largest school district in the USA, guidelines allow for the closing of schools but don’t outline the plan for if that happens, nor what would prompt schools to close.

That’s despite the state’s record COVID-19 cases this month. The state has surpassed 315,000 confirmed cases. Nevertheless, Florida last week ordered all schools to reopen in person, five days a week.

In Volusia County, Florida, the district designated a schools-specific team of epidemiologists and contact tracers to track and manage the spread of coronavirus, Patricia Boswell, administrator of the county’s health department, said in a meeting Wednesday.

In Indianapolis, the public schools’ plan explicitly notes, “The district must be able to quickly implement e-learning for 100% of students if rolling closures occur,” although positive COVID-19 tests will be handled on a “case-by-case basis.” 

The School District of Philadelphia, the largest in Pennsylvania, takes a similar approach.

“If we have high rates of community spread and we believe the school system is contributing to that, in some important way, that would be our criteria to shut down the entire system,” Philadelphia Health Commissioner Thomas Farley told news channel WPVI-TV.

In Memphis, Tennessee, Shelby County Schools outline a more comprehensive plan. It doesn’t indicate a case threshold for closing but says, “Depending on the extent of positive cases within a school, a school may need to close for up to two weeks and then stagger student attendance upon restarting.”

USA TODAY’s findings matched the conclusions of the Center for Reinventing Public Education, a nonprofit group in Washington state that’s been reviewing plans.

Few, if any, state-level plans for reopening schools address what schools should do if a student or teacher tests positive for COVID-19, said Bree Dusseault, a practitioner-in-residence at the Center for Reinventing Public Education. 

Of the few plans that do address COVID-19 infections among students or teachers, plans range from shutting down the school for 24 to 48 hours for deep cleaning, then resuming classes, to sending all kids home for remote learning for two to four weeks, Dusseault said.

If students are sent home because of a COVID-19 case, “it’s going to be critical that districts ensure students have continuity of access to the same curriculum, teachers and socio-emotional support staff,” she said.

For districts that do not have a plan, the response to an infected person in school should depend on how high transmission is in the community, said William Hanage, an epidemiology professor at Harvard University.

“If there’s one case and it’s a single introduction to the school, and there’s a low rate of community transmission, it might be sensible to shift just that group to education at home for a period of time,” he said.

That’s different from if infections show up in multiple classes, multiple times, he said.

“If you can keep community transmission low, it’s reasonable to think schools can be reopened and outbreaks within schools can be controlled,” Hanage said. “Once community transmission becomes high, you need to think about doing something different.”

Contributing: Erin Richards, USA TODAY; Cassidy Alexander, Daytona Beach News-Journal; Arika Herron, The Indianapolis Star; Rebecca Plevin, Palm Springs Desert Sun

This article originally appeared on USA TODAY: Back to school reopenings: How many COVID-19 cases would close school?