Posted on by Californiacontrarian

I’m Confused !


When my wife read this title,she said, “So what else is new?” 

Granted I am confused about a lot of things, but here I am specifically confused about stuff related to Covid testing. In a recent Wall Street Journal editorial I read that there has been 186 million Covid tests done since it ostensibly came from Chinato the US this past winter. Of these 186 million tests the US has had 12.7 million cases, i.e. 12.7 million positive tests out of 186 million. Now I agree that 12.7 million is a lot of anything, however my question involves all of the negative tests. If only 12.7 million tests were positive, it means that 173.3 million tests were negative. Now 173.3 is a lot of anything, but “wow” . . . that is a lot of negative tests! Who is getting all of these negative tests? 

If the majority or even a lot of these 173.3 million negative tests are the result of contact tracing, is it reasonable to say that contact tracing is not as effective as advertised? Where I live, testing for Covid is ubiquitous and yet we are in the midst of a “surge” of cases. If contact tracing and the subsequent testing that occurs as a result of contact tracing was an effective way to stop the spread of the virus, then why are we surging in the face of increased testing? A quandary? A dilemma? 

I’m confused!

Actually the answer is quite simple. We are in the midst of a pandemic caused by a very infectious virus, and more importantly the present estimate is that 40% of the positive cases are asymptomatic. Of those that have symptoms (the other 60%), the present estimate is that 80% of those with symptoms have mild symptoms. When combining the number of asymptomatic (40%) and mildly symptomatic [(100% – 40%) x 0.8 = 48%], it means that 88% (40%+48%) of positive cases do not realize that they have the virus. 

If upwards of 80+% do not appreciate that they could well have the virus, then they most likely have no incentive to get tested. That sounds reasonable, however who are those that comprise the 173.3 million negative tests? Okay, foreign and many interstate travelers are often required to have a negative test. Certain occupations require periodic negative tests, as do those who care for the most vulnerable. However, these groups do not add up to 173.7 million negative tests, and probably do not even add up to 100 million. This still leaves a whole bunch of negative tests unaccounted for. Can the Karens and the Kens be getting continued repeated and repeated again tests every time they sniffle once or go to the grocery store? Even if these are the Kens and the Karens that are wearing masks when alone in a car or when taking out the garbage . . . 70 million tests?

I’m still confused!

The other dilemma with this deluge of testing is the incidence of false positive tests.

Just last month the FDA put out an alert about false-positive rapid antigen COVID-19 tests. The probability of false-positive tests goes up as the prevalence of the disease goes down.

According to data from the FDA, if an antigen test has 98% specificity, and 10% of the population has the disease, 20 out of 100 people who test positive will not have the virus. This already seems high but check out what happens if the disease prevalence drops to 1%: 70 out of 100 people who get a positive result, will get a false positive.”

OMG! I wonder how many of the millions being tested are re-tests? (e.g. “I can’t believe that my test was positive. I feel fine. I doubt that I have the virus. I am going to get retested, and if negative, I’ll get a third test . . . just to break the tie, and the a fourth . . . just to be absolutely sure.”)

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