Abstract
The Severe Acute Respiratory Syndrome (CoVID 19) provoked by Coronavirus 2 (SARS CoV 2) require science-based responses. The aim of this work is to assess pitfalls found during the search of viral genomes due to sampling timing, swabbing, storage, heat-infectivity inactivation and further sample processing. According to several meta-analysis, on the day of symptom onset, the median false-negative rate is estimated to be 38% and decreased to 20% on day 8 (3 days after symptom onset) then increased to 66% on day 21 suggesting that rRT-PCRs adds little information immediately after exposure. RNA isolation from samples requires cautious handling using RNase-free solutions, pipet tips and glassware. The rRT PCR detection limits are estimated between 39 and 779 copies/mL but 3000 to 20.000 copies/ml for the antigen test. External cross contamination by imperceptible splatting requires risk management integrating the Pharmacopoeias by processing at least 10 negative contiguous to 10 positive controls in each sennries of 100 tests. . For Ct >34 it was suggested no transmissible disease. The detection of antibodies one month or later after clinical signs may confirm positivity. Lack of immune response in non-immune compromised asymptomatic people may invalidate positivity. False positive disrupts efficiency for containing infections and leads to societal anxiety undermining health workforce. Because spurious methods create confusion, each step of diagnosis requires quality-control and risk assessment, knowing that rRT PCRs amplify more than 10.000 million times the signal of 1 viral element
Highlights
Emerging respiratory viral infections like the Severe Acute Respiratory Syndrome (CoVID 19) provoked by Coronavirus 2 (SARS CoV 2) require science-based responses
The rRT-PCR is a complementary diagnostic tool given its high specificity for SARS CoV2
The lack of immune response in non-immune compromised asymptomatic people may invalidate the positive rRT-PCR SARS CoV 2 results the diagnostic accuracy of antibody tests to determine if a person presenting in the community or in primary or secondary care has SARS-CoV-2 infection, or has previously had SARS-CoV-2 infection, and the accuracy of antibody tests for use in seroprevalence surveys showed for pooled results for IgG, IgM, IgA, total antibodies and IgG/IgM, low sensitivity during the first week since onset of symptoms, rising in the second week and reaching highest levels in the third week
Summary
Emerging respiratory viral infections like the Severe Acute Respiratory Syndrome (CoVID 19) provoked by Coronavirus 2 (SARS CoV 2) require science-based responses. The Nucleic Acid Amplification Techniques (NAATs), the reverse transcriptase real-time polymerase chain reactions (rRT-PCRs) are largely used for detecting infected agents [2]. Eye shield, grown, gloves and equipment must be available during sampling as well in clinical and in laboratory settings These mechanical barriers do not protect the samples (do not avoid viral RNA to stick on gloves or on other surfaces). The tubes containing RNA viruses require special care due to the degradation of the viral genes during shipping, freezing, storage, thawing and heat-infectivity inactivation. Numerous laboratories preform sample-infectivity inactivation by heating at 56°C This procedures disrupt the integrity of the single-stranded viral RNA and adversely affects the quality of viral detection, especially for samples carrying low viral loads [22]. Changing gloves after sampling each individual seems unrealistic in contexts of massive screening with restricted health budgets
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