CDC PCR tests16 Dec 2021 23:55
CDC Admits Its PCR Tests From 2020 Were Contaminated and Caused "False Positives"
????@COVID19Up: Faulty SARS-CoV-2 testing kits developed by the CDC in the early weeks of the pandemic were not only contaminated but had a basic design flaw that caused false positives, according to an internal review by the agency.
In mid-February 2020, the CDC acknowledged that the kits were flawed, and in April 2020, officials at the FDA said that poor manufacturing practices had resulted in contamination of the test kits. The new paper, published in PLOS ONE on Wednesday (Dec. 15), presents the results of the CDC's own internal investigation into the problems with the tests.
The PCR test was designed to detect three distinct regions, or target sequences, of SARS-CoV-2's genetic material. The test kits contain a set of what are known as primers—which bind to and make copies of the target sequences—and probes—which produce a fluorescent signal when these copies are made—indicating that genetic material from SARS-CoV-2 is present.
The primers and probes need to be carefully designed so that they bind to the target sequences and not to each other. In this case, that did not happen. One of the probes in the kit sometimes bound to one of the primers, producing the fluorescent signal and generating a false positive.
The investigation also confirmed that the test kits had been contaminated with synthetic fragments of SARS-CoV-2's genetic material. These synthetic sequences, which are often used to ensure that the tests are working properly, were manufactured at the same CDC lab where the test kits were undergoing a quality analysis.
The contamination suggests that the agency violated standard manufacturing protocols, officials have said.
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