coronavirus covid-19 illustration file photo cdc dark background

This illustration, created at the Centers for Disease Control and Prevention, reveals the structure of the novel coronavirus. The illness caused by this virus has been named COVID-19.

After declining steadily through August and most of September, coronavirus hospitalizations are increasing in Pennsylvania, and nearly half of those patients are in facilities in just four counties, an LNP|LancasterOnline analysis shows.

Philadelphia, York, Allegheny and Lehigh counties contain about a quarter of Pennsylvania’s population but together averaged 273 COVID-19 patients per day over the past two weeks. That’s nearly half of the statewide figure of 552, according to the state Department of Health.

And that average daily patient load statewide is up more than 20% from two weeks ago, when it stood at 458.

Many people who contract COVID-19 — especially younger ones — experience only mild symptoms and do not need to be hospitalized. But health officials continue to urge preventive measures, including masks and social distancing, to fight the spread of the virus, which has killed 8,299 Pennsylvanians since March.

The 20% increase in COVID-19 hospitalizations in Pennsylvania over the past two weeks parallels a 26% increase in average daily rates of new cases over the same period.

COVID-19 hospitalizations in Pennsylvania

This screen shot from the Department of Health's website shows the COVID-19 hospitalization trend in Pennsylvania since mid-June. After a lengthy decline, the rate recently began increasing.

Here are the 10 counties whose hospitals, as of Thursday, had the highest daily average of COVID-19 patients from Sept. 25 to Oct. 8:

1) Philadelphia — 106

2) York —74

3) Allegheny — 59

4) Lehigh — 34

5) Montgomery — 30

6) Montour — 24

7) Dauphin — 19

8) Delaware — 18

9) Lancaster — 17

10) Chester — 16

All of the top-10 counties saw their daily average number of COVID-19 patients increase from their levels of two weeks ago. The sharpest jumps were in Lehigh, which doubled from 16, and in Montour, which nearly tripled, from 9 patients. Lancaster’s average increased from 13.

The Department of Health’s website displays hospital data back to June 14, when the state’s daily average number of hospitalized COVID-19 patients stood at 1,062. It dropped to a low of 452 on Sept. 27, and it has been increasing since then, along with the overall rise in new COVID-19 cases.

Per capita rates

Many of the counties that rank high for hospitalizations are also among the state’s most populous. So another way to look at the data is the per-capita rate of hospitalizations per 100,000 population.

But that can skew the results in rural areas, where one hospital might serve several counties, making it appear that the county where the hospital is located has an unusually high rate of hospitalizations.

That is likely a factor in the data for rural Montour County, for example, which has only 18,000 people but is home to Geisinger Medical Center, which serves a multi-county area. Montour had a rate of 129 hospitalized COVID-19 patients per 100,000 population, which far exceeds any other county.

Following are the 10 counties with the highest per-capita rates of COVID-19 hospitalizations over the past two weeks.

Philadelphia, which has the largest number of hospitalizations, would rank 11th on the per-capita list, at just under 7 per 100,000 population. Allegheny would rank 15th, at 5 per 100,000, and Lancaster would rank 22nd, at 3 per 100,000. The statewide rate is 4 per 100,000.

Here are 10 counties with highest average daily number of hospitalized COVID-19 patients per 100,000 population:

1) Montour — 129

2) York — 16

3) Bradford — 16

4) Union — 14

5) Northumberland — 11

6) Mifflin — 11

7) Lehigh — 9

8) Lebanon — 7

9) Blair — 7

10) Dauphin — 7