Making Sense of COVID-19 Testing Data Published by OC HCA

The OC HCA reports two kinds of test data labelled spec and repo. What’s the difference? It’s actually the same data. To better understand it, let’s start with a simple hypothetical account of a COVID-19 PCR test:

It’s September 1. I go to a test center and get a PCR test for COVID-19. My test specimen is sent to a lab for analysis. The result is negative. Two days after my test on September 3, that result is reported to me. The next day, September 4, the result is reported to the state. The state then shares it with OC HCA.

On September 5, OC HCA reports 5305 new tests. This is the number you’ll see displayed on the OC HCA dashboard that day. My test is one of those reported tests. On that day, OC HCA also reports 7118 daily spec tests for September 1. My test is included in that number, too. It is not published on the dashboard but it is stored in their database and available from their REST service. The next day, the dashboard will be updated.

The reported date for my test is September 5. The administered (spec) date was September 1. There was a delay of 4 days in reporting tests.

That’s the difference between repo and spec test data. The data is available directly from the OC HCA REST server here:

Here’s a sample record returned by that API:

      "attributes" : {
        "date" : 1599289200000, 
        "daily_neg_spec" : 2746, 
        "daily_pos_spec" : 139, 
        "daily_spec" : 2885, 
        "tot_spec" : 720280, 
        "tot_pcr_pos" : 59324, 
        "cdph_tpp" : 3.790459966, 
        "tot_test_repo" : 696048, 
        "daily_test_repo" : 5305, 
        "daily_7day_avg" : 6283.857143, 
        "ObjectId" : 167

More data on testing and reporting delays can be found here:

My tip for getting the most timely and accurate info on the progress of COVID-19 in Orange County? Look at test positive rate in cells N7 or N8 in this spreadsheet and compare to preceding days:

Making Sense of COVID-19 Testing Data Published by OC HCA

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