I applaud the City of Del Rio government’s near-daily Facebook chart that tells us the following (as of July 16):
• Number of tests submitted – 6,348
• Number of positive patient results – 837
• Number of negative patient results – 4,976
• Number of pending results – 515
• Number of patients recovered – 141
• Number of active cases – 696
• Number of deaths – 8
• Number of cases contracted by international travel – 25
• Number of cases contracted by domestic travel – 26
• Number of cases contracted by community spread – 36
• Number of cases contracted by personal contact – 49
• Number of cases pending contract method – 701
Yes, the information and the numbers are right there. However, they did not mean anything to me. I wanted to know how much infection risk there was out there and how it was trending. I’m talking about the positivity rate. So, I figured it out for myself and then shared it on Facebook with each new chart. I’m all about sharing information.
After a false start, respectfully corrected by others on Facebook, I developed the effective positivity rate formula. You start with the total tests given – 6,348. Not all of those tests have results yet, so you deduct the pending tests – 515 – to get the number upon which you will base your percentage. That gets you 5,833 tests that have results. Now you divide the positive test number – 837 – by the total test results number – 5,833. That gives you a positivity rate of 14.34 percent. Then I take that percentage and apply it to the pending test number – 515 – and see that 74 of those pending tests will come back positive.
Well how about that, I see that the city is now adding the positivity percentage in the explanation under the chart. Did I make a difference? (Oh, darn it all, now I see I reported a lower percentage on Facebook today based on the wrong numbers and got everyone’s hopes up. I have corrected it. My sincere apologies.)
The positivity rates have steadily increased from 7.8 percent on July 1 to 10.76 percent a week later on July 8, and another week after that we were 14.2 percent on July 15. I’m not going to talk about death rates except to note that we went from 0 to 18 (official cause of death still pending) in just one week – July 9-16.
The upward trend of the positivity rate has nothing to do with how many tests are performed. The rate will go down only when less people test positive per 100 tests given. Right now, if there are 100 shoppers in Walmart or HEB, you can bet good money that about 15 of them will be COVID positive – and they may not know it. And judging from the arguing on Facebook, that number is just going to rise because we will not unify on a plan to stop COVID. That makes too many asymptomatic and symptomatic COVID carriers out there with the potential to infect me. I don’t think you will be seeing me out and about too much. It’s just too risky!
Willie Braudaway strives to make life better as a librarian, genealogist, and member of various community organizations. Contact her at firstname.lastname@example.org.