Routine blood analysis greatly reduces the false-negative rate of RT-PCR testing for Covid-19.

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Davide Ferrari
Eleonora Sabetta
Daniele Ceriotti
Andrea Motta
Marta Strollo
Giuseppe Banfi
Massimo Locatelli


COVID-19, RT-PCR, blood test, WBC, aspartate aminotransferase, lactate dehydrogenase


Background: The COVID-19 outbreak is now a pandemic disease reaching as much as 210 countries worldwide with more than 2.5 million infected people and nearly 200.000 deaths. Amplification of viral RNA by RT-PCR represents the gold standard for confirmation of infection, yet it showed false-negative rates as large as 15-20% which may jeopardize the effect of the restrictive measures taken by governments. We previously showed that several hematological parameters were significantly different between COVID-19 positive and negative patients. Among them aspartate aminotransferase and lactate dehydrogenase had predictive values as large as 90%. Thus a combination of RT-PCR and blood tests could reduce the false-negative rate of the genetic test. Methods: We retrospectively analyzed 24 patients showing multiple and inconsistent RT-PCR, test during their first hospitalization period, and compared the genetic tests results with their AST and LDH levels. Results: We showed that when considering the hematological parameters, the RT-PCR false-negative rates were reduced by almost 4-fold. Conclusions: The study represents a preliminary work aiming at the development of strategies that, by combining RT-PCR tests with routine blood tests, will lower or even abolish the rate of RT-PCR false-negative results and thus will identify, with high accuracy, patients infected by COVID-19.


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