Ricketts said there are two general indicators of spread that could prompt a school closure decision.

One scenario would be if health officials determine that the infection rate in a community is approaching 1% of the population.

He suggested that could be determined with the help of computer modeling as officials get better at tracking the spread of the disease. He said if officials see a spike in flu-like symptoms but a drop in flu cases, that could be an indicator of community spread.

Ricketts said the other rule of thumb would be when there are confirmed cases of COVID-19 in the community that can’t be traced back to a known source.

He said that in the Omaha metro area, because of its greater population, the threshold that officials would be looking for is two cases. For the Lincoln area, it would be one or two cases, he said.

In rural parts of the state, a single confirmed case of community spread could trigger a shutdown, he said.

In that event, schools would be closed in an entire educational service unit, with neighboring school districts having the option to close. The state has 17 ESUs, with Omaha, Sarpy County and Lancaster County all having their own.