Updated Daily
This page plots the COVID-19 case counts in several southwestern Pennsylvanian counties. It uses the data that the Pennsylvania department of health has been posting on COVID-19 test results every day at noon.
New Cases over Time
This chart shows the number of new confirmed daily cases in Allegheny and Westmoreland Counties.
This chart shows the number of new confirmed daily cases in Pennsylvania.
Prevalence Over Time
The following plot shows the number of confirmed cases per 100,000 in the population. While Allegheny has more total cases than neighboring counties, the number of cases per resident is lower than adjacent counties.
Governor Wolf’s Criteria for Reopening
In a press conference on April 22, 2020, Governor Wolf outlined criteria for reopening the commonwealth. One criteria that will be used is whether a county has had fewer than 50 positive tests per 100,000 residents over a 14 day period. On May 1, Governor Wolf announced the first counties that would transition to the ‘Yellow’ partially reopened category. These counties had an average of 15.8 positive tests per 100,000 residents in the 14 days prior to the announcement.
The following plot shows how the state and various counties are doing compared with this criteria.
Changing the vertical axis scale shows counties with lower case rates more clearly.
Test Positivity Rates
Pennsylvania has been posting positivity rates for the most recent past week on their Early Warning Monitoring System Dashboard. The positivity rates posted here are different from those that have been published by some other sources. For more information, see the blog post I wrote on the topic.
The following figure shows the positivity rate over time based on this source.
Data Tables
The data used to generate these plots can be found in tabular format in this spreadsheet.
For more information, the Allegheny County health department provides a breakdown of the number of cases by municipality here.
Awesome collection and representation of data. Thanks!
Yes thank you! Why doesn’t PA have a better overall graph and tracking??
Can you do a table of daily county new cases? And a logorhithmic graph?
I added a table of new daily cases in Allegheny county. The growth in cases in the county is no longer exponential so I think a linear scale shows this set of data better than a logarithmic scale would.
Hi Jon been following your charts and graphs. Can you give a reasoning for the uptick in cases yesterday?
I don’t know the reason. I wouldn’t read too much into the datapoint for a single day. I would note though that the total number of tests reported today was higher than any day since April 11, 2020, and the percentage of tests that were positive in the state dropped. So it may just be that more cases are being detected (a good thing) rather than there being an uptick in the number of infections. We want both the total number of cases, and percentage of positive tests, to be going down.
Ok thanks! Is that happening yet?
Thoughts on these occasional “spike days”? What could they be?
In some cases, a ‘spike’ in new cases reported in Allegheny County is just an artifact of the reported as it coincides in a spike in the number of test results reported. This happened on 4/18/2020 and again today (4/23/2020). But I would also consider that the daily number of new cases in Allegheny county are small enough that a single infected individual could cause a spike in numbers if they infect enough others. Google ‘super spreader event’. So there’s going to be some variability in the day to day numbers. I wouldn’t read too much into the numbers for a single day, the trend over several days is more important.
Hey Jon! so I was reading the GOV plan again, and it says the regions have to average less than 50/100000 people per day. I know you say here that we meet that, but wouldn’t be we take the average over 14 days and we can’t have above the 50/100000 (so 600)? Instead of 50 per day?
hi Jon! me again so I cam across this nice chart someone put togther on twitter…wondering if you could this?
https://mobile.twitter.com/jmelwert/status/1253782150756868101
Apparently the state has provided conflicting guidance about whether it is 50 cases per day or 50 cases total over 14 days per 100,000 residents. See this:
https://www.wesa.fm/post/state-website-sends-mixed-messages-about-when-counties-may-be-eligible-reopen#stream/0
My chart above assumes the limit is 50 cases total over 14 days per 100,000 residents. I think this is the correct interpretation, but I will revise if I find out otherwise.
ok thanks Jon! I figured you were correct
I would like to rekindle my ask for a log scale graph. Seeing how close we are to flattening would be heartening.
The state just released the counties moving to the yellow phase and we are not on it. Could you provide reasoning as to why? Since you graph is showing we are under the threshold?
See the latest post on my home page.
Thanks Jon—so you think it’s the density that is posing the risk?
That is the Governor’s concern, Allegheny county should wait because of its high density. As I wrote in one of my blog posts, I personally don’t think density should be considered a negative factor though.
How about a line graph with a seven or 14 day moving average line to show the downward trend?
Good idea, I made the update.
Thanks. You’re a few days behind on the graph. Wondering if it will ever turn down again. Probably not with the opening.
Yes, I am surprised and concerned the number of new cases have held steady. The impact of reopening isn’t present in the numbers yet because there is a delay between becoming infected, developing symptoms, being tested, and then having the results being reported. So the number of new cases being reported today is really a reflection on the number of infections 2-3 weeks ago. Hopefully the county hiring more contact tracers will help, but that remains to be seen.
Anyway you could track percent positive of cases? Seems like testing has increased but wondering if positive cases have too
That is shown in the plot with the title: ‘% of Test reported each day that are positive.’
We went “yellow” on the 15th right? We are two weeks in. I hope we don’t see a burst the next few days.
Not happy to see daily numbers remains between 10 and 30. Yes, 7 day average counties to go down slowly but we could have stayed shit two more weeks and had a much steeper decline.
Idiotic. I just don’t get it.
I see you’re condensing the graphs to fit the page. Could you provide a link to the full graph?
Thanks for your diligent efforts. I check this page every day.
You’re welcome.
Close the damn bars.
Seriously, you need to get the post gazette to post your graphs daily. We need a wake up call. They are doing a terrible job of informing the public about what is going on. They have ZERO visual aids.
No more updates? Regardless, thanks for all your efforts.
Thanks for the catch. I’ve still been updating the charts in a google doc. There was an issue with how the blog linked to them so they weren’t updating, I’ve fixed it.