Until a vaccine is in widespread distribution, the number of coronavirus cases appearing in a community is an important metric to watch.

The new case rate, as it’s called — often calculated as the number of cases diagnosed daily per 100,000 people — isn’t as useful as positivity rate or hospitalization count in measuring how close our health systems are to being overwhelmed, because many people infected don’t get immediately sick or end up in a hospital.

But health experts don’t know how to predict exactly who will get deathly ill, and also don’t know the long term effects of contracting the virus. Some early studies have shown even a mild case of COVID can cause headaches or breathing problems down the road.

New case rate is basically a measure of how well a region is keeping the virus contained and eliminating spread.

The chart below allows you to gauge how Philadelphia is doing compared to the statewide and national average. It will stay updated, and changes often, so bookmark this page to check back.

(If you’re viewing on mobile you may need to flip your phone sideways to view the whole thing.)

What the graph shows, specifically, is the percent difference in the city’s new case rate compared to Pa. (orange) and the U.S. (blue), using a 7-day average of reported coronavirus positives divided by the region’s population.

The city count makes up the horizontal axis. If the line is below the axis, Philly’s case rate is lower (a good thing). If the line is above, Philly’s case rate is higher (not so good).

As of Dec. 10, the average count for Philly over the past week is around 66 new cases daily for every 100k residents. That’s higher than it’s been so far to date — a near 20% rise over last week, according to the STAT News tracker.

Though the city was for a while experiencing more cases than many other parts of the state, that’s changing.

Philly’s new case rate is lower than Pennsylvania’s right now. The state is experiencing a major spike, with the number of new cases discovered per 100k residents averaging around 78. That’s a nearly 50% jump from a week ago.

Around the U.S., case rates vary widely from state to state. The national average is around 64 new cases per 100k residents, a stat that’s grown just over 25% since last week.

Danya Henninger is director and editor of Billy Penn at WHYY, where she oversees the team, all editorial decisions, and all revenue generation — including the membership program. She is a former food...