Wednesday, April 15, 2020

They’re NOT lying… they’re just jargonizing?

What is a test?
Up until now there has been only one type of test which is intended to tell us if the person is carrying the virus.  Actually,  the test does  not look for the virus, it looks for a piece of the virus, and to be more accurate, it looks for a piece of what is thought to be the specific virus.    
The virus we are looking at is a part of a large family called coronavirus, which is very wide spread and is the second most common cause of common colds. 
 The test looks for genes that some think is specific to the SARS-C0V-2 virus, but since not all coronaviruses have been studied, it is not certain that the test is detecting is the gene that is specifically from the SARS CoV-2 virus .
We cannot say that the test is as specific as we would like.  
That may be why there is a lot of concerns about FALSELY POSITIVE tests.

Importantly, we assume that when the test is done, it is done correctly; that when the swab was put in someone’s nose or throat that was done correctly, that the swab was labelled correctly, that it was transported correctly, that it was put in the machine correctly, that the machine was working properly, that the result was read correctly and recorded correctly and sent back to the right person.  LOTS of opportunity for error.  There is a lot of evidence that when tests are done in high stress the risk of error rises. 
So we have lots of reasons to be careful (suspect?) of all test results, positive and negative.

What is a case?
The test as developed has a big problem because the laboratory cannot confirm the test result is right because patients can have symptoms, or may not, may be sick or may not.  If there is no marker, can you say for certain that the test result is correct?

To reduce some of the confusion, public health excludes testing people without symptoms.  You cannot get a positive test in a person without symptoms if you don’t test them.   So we know very little about people with a positive test when they have little or no symptoms.  Maybe this is what a CARRIER STATE, or maybe it is a FALSE POSITIVE laboratory error.

If you only test people with symptoms, and you get a positive test, does that mean the symptoms are associated with SARS CoV-2?  Maybe, but maybe not.  False positives are just as possible in people with symptoms as in people without symptoms.

Also, when people with symptoms of cough and sore throat and fever are tested, only about 4 percent are positive.  That seems VERY LOW.  Does that mean when 96 percent of people with fever and cough and a sore throat in the presence of this epidemic have a negative test?  

Either there are many other viruses around, or this is an example of  FALSE NEGATIVE laboratory error.

All this says that at this point we know very little about what test results means, about its sensitivity or specificity or its accuracy.   Should questionable test results decide what is or what is not a case?

What is a "new death count"?

When many people hear the term “new death count” they may understand that to mean a person who recently acquired the virus, got sick and then very sick and then died. 
But the single group that makes up the majority of the “new deaths count” are elder people, the majority over 80 years, mostly frail and living in nursing homes.  They became sick weeks ago, were admitted to hospital, maybe ended up in intensive care with a breathing tube.  They have been kept alive through mechanical support until their body finally gave up and passed away.  So yes, their death occurred today, but in reality it was expected for days or weeks.  Calling this a "new death" is a tad disingenuous, and needs a different classification.
When you hear a public health official say they expect the number of "new deaths" to rise, they are saying there are lots of these folks lying in beds, and one day, their day will come.

So as you listen to the nightly review of COVID-19 statistics, listen carefully and understand what you are being told.  Maybe it is just language confusion,
But maybe not.

No comments:

Post a Comment

Comments, thoughts...