BREAKING! Study Shows Inactivation Process In Samples For COVID-19 Diagnostics Could Lead To High Rate of False Negatives!
: A team of medical and biotech researchers led by Dr Chaofeng Ma of Xi'an Center for Disease Control and Prevention in China had initially hypothesized that viral inactivation may contribute to false negatives.
The researchers subsequently tested several inactivation methodologies to determine if and to what extent they reduce detectible virus in a clinical sample and the results were shocking.
The study findings appear in the Journal of Clinical Microbiology
, a publication of the American Society for Microbiology. https://jcm.asm.org/content/early/2020/05/28/JCM.00958-20
Typically, to protect medical laboratory personnel from infection when testing clinical samples for SARS-CoV-2, most laboratories inactivate the virus before testing.
In the past, the effect of inactivation on the detection of results had not been determined, but the rate of false negatives for one time testing of inactivated virus has been estimated to range from 30% to 50%.
The research team took clinical samples from 63 patients who had been infected with SARS-CoV-2. They first used a technology called digital PCR to determine the total number of virus particles in each sample.
The researchers then inactivated virus from the samples and determined how much less virus was detectible at 2 sites within the genome, a gene that codes for the "nucleocapsid" protein and a section of genome called ORF 1ab.
Significantly, the first inactivating treatment used a reagent called TRIzol and destroyed 47.54% of nucleocapsid genes, and nearly 40% of ORF 1ab.
Also the second inactivation treatment heated the samples to 56°C for 30 minutes and reduced the quantities of the two sections of genome by 48.55% and 56.40%, respectively.
Further heating to 80°C for 20 minutes reduced viral copy numbers further, and boiling, or autoclaving at 121°C left virtually no detectible virus.
The researchers suggested that future studies should include inactivation reagents besides TRIzol.
The study findings has huge implications as many of these protocols were being used in labs across the world doing COVID-19 RT-PCR testing and indirectly reflected on the inaccuracy of testing results across the globe and also the dangers of many infected individuals with false negatives walking around and spreading the disease let alone their own health conditions.
Thailand Medical News contacted WHO, US CDC, US NIH and the US FDA with regards to findings from this new study but officials declined comments.
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