Study: Current COVID-19 Test by the CDC is Wrong Half the Time

A study published in the July edition of the International Journal of Geriatrics and Rehabilitation looked into the accuracy of the current COVID-19 test issued by the CDC.

The study retested the samples provided by the Connecticut State Department of Public Health with a second test.

The first test was done using the CDC RT-PCR Diagnostic Panel.

A total of 20 samples was issued by the Connecticut DOH to the study. 10 samples tested positive, and 10 samples were tested negative for SARS-CoV-2, the virus that causes COVID-19.

The two sets were then subjected to a second test in the study. This time it included the respiratory cells where the nasal or throat swab was taken from.

The inclusion of the cells in this second test is vital since viruses multiply inside the cells. This step detects the presence or absence of the SARS-CoV-2 virus inside the human cells, and that means infection.

The study found that out of 10 positive samples, only 7 were confirmed to have the SARS-CoV-2 virus.  3 samples did not have the virus. A false-positive rate of 30%

Among the 10 that tested negative, 2 were found to actually have the virus—a false-negative rate of  20%.

Therefore, in 10 RT-PCR tests done using the CDC kit, 2 will be falsely negative, and 3 will be false positive. Half of the results will be wrong.

 

 

How can the CDC kit have false positives?

The CDC kit only examines the fluid and not the cells of the samples obtained from a person. This fluid sample may contain viruses or only fragments of the viral RNA or ribonucleic acid of the virus.

These fragments are detected by the CDC kit and can result in a positive test. Viral fragments in the fluid do not necessarily mean there is an infection because the virus should be present inside the cells to produce an infection.

Sometimes, the fragments are there because the body’s immune system already destroyed and broke up the viruses before they can enter the cell.

What explains the false negatives?

False-negative means there is a viral infection, but the test says there is none. For viral infections to happen, the viruses have to enter the cells.

In the CDC test, the cells are separated by centrifuge, and only the liquid part is tested.

In contrast, the added test done in this study sequenced the viral DNA inside the cells. This additional method provides a more accurate analysis of the presence of the virus.

A negative CDC test can mean that all the viruses are already inside the cells and multiplying. Another reason is that the viral load in the sample is very low.

A third reason for producing false negatives is that inhibitors to the test coming from human cells or other microbes collected can be present and interfere with the test.

These reasons are not present with the added DNA sequencing that this study did.

The CDC test has been reported to have false-positives before

This is not the first report about the inaccuracies in the CDC test kit. In a study published in Experimental Neurobiology in April 2020, the investigators detected false positives in the absence of SARS-CoV-2 DNA. A quote from the study says,

We strongly suggest that the CDC protocol to be thoroughly re-examined before it is further distributed as a detection kit for SARS-CoV-2.

In April, Washington Post reported Contamination at CDC lab delayed rollout of coronavirus tests.

Shortcomings with the tests were first noticed in late January, after the CDC sent an initial batch to 26 public health labs across the country.

According to those with knowledge of what unfolded, false-positive reactions emerged at 24 of the 26 labs that first tried out the kits in advance of analyzing samples gathered from patients.

 

“Only two of them got it right,’’ said a senior federal scientist who reviewed the development of the kits and internal test documentation, and who concluded that the false positives were caused by contamination that occurred at the CDC.

The problem with false positives was also detected in Australia, a group of scientists studied a commercial RT-qPCR test kit and found that its positive predictive value is only 55.56%!

The limitation of this study

This study tested only 10. Another study involving more samples should be done to validate the test and make the results more robust.

If the added DNA sequence determination is accepted as a second test for detecting COVID-19 cases, it takes 24 to 48 hours to have the results because of the additional steps, and automation is not yet possible.

The importance of having an accurate test

False-positive tests can lead to wrong diagnosis and unnecessary quarantines and treatment and psychological trauma.

A false-negative test can send back an infectious person to their homes or work and contaminate more people. It also leads to misdiagnosis and delays in treatment.

The number of COVID-19 cases determines if lockdowns, school closures, and business reopenings should happen or not. These have consequences in the overall economy.

Knowledge about Covid-19 is rapidly evolving. Information may update as new researches are done. Stay current by subscribing.

Feel free to share.

Don’t Get Sick!

Reference:

Sin Hang Lee. Testing for SARS-CoV-2 in cellular components by routine nested RT-PCR followed by DNA sequencing. , International Journal of Geriatrics and Rehabilitation 2(1):69- 96, July 17, 202

As an Amazon Associate, I earn from qualifying purchases.