Pictured here are Pennsylvania Gov. Tom Wolf, left, and Health Secretary Dr. Rachel Levine.

Now that Gov. Tom Wolf announced the entire state will move to "yellow" on June 5, LNP | LancasterOnline is just getting to the bottom of where one of the often-cited metrics to reopen came from.

How did the Wolf administration come up with the metric that counties with fewer than 50 new cases for every 100,000 residents over 14 days can begin to open up? The basic formula was created by epidemiologists at the Department of Health and is recommended by the Centers for Disease Control & Prevention, the state Department of Health said. 

State Department of Health Secretary Dr. Rachel Levine said the metric, which says an area must not have more than 50 new cases of coronavirus per 100,000 residents over a 14-day period, is one of several criteria -- such as hospital capacity and contact tracing and testing abilities -- that Wolf’s administration set for moving counties from “red” to “yellow.”

The 14-day metric has been widely criticized by Republicans as made to keep more of the state under the stay-at-home order, as hospitalization rates fall and new cases increase in specific communities like nursing homes. During a press conference last week, Republican County Commissioner Josh Parsons questioned the source of this metric. 

"It's not clear where that came from," Parsons said. "It's not based in science."

In a call with LNP | LancasterOnline last week, Levine said the metric is an incidence rate, which describes how quickly a disease occurs in a population, according to the Centers for Disease Control. The CDC recommends this as a measure showing “moderate” community spread, she said. This is internal CDC information, a spokesperson for the Department of Health said.

“It really was a scientific, data-driven analysis, but it was an attainable goal,” Levine said. “It looked like this would be something that counties could obtain, looking at all the other [criteria].”

Wolf today is expected to announce loosened restrictions on more parts of the state and, potentially, the move of several counties from yellow to green. 

“We have let counties go that were 52 per 100,000,” Levine said, but that counties with a rate of 85 or 100 per 100,000 residents “is reflective of significant community spread.”

It seems, though, per Wolf's announcement Friday the state will allow regions that have higher numbers to reopen even if their new case rates do not drop below this 50-cases-per-100,000-residents metric.

As of Thursday, the county has had 326 new cases in the past seven days, up from 294 in the previous seven days, according to the Pennsylvania Department of Health. Combined, the two-week total pushes the county to 114 cases per 100,000 population over the most recent 14-day period. The local score had been falling and stood at just over 100 earlier in the week.

Other states like New York and Maryland chose other metrics like new hospitalization rates as key markers to measure whether an area is ready for limited reopening. 

Levine said it was a "specific" decision to use new cases over new hospitalizations. In a follow-up email, a Department of Health spokesperson said hospitalization rates would have limited rural areas that have few hospitals from reopening.