COVID-19 laboratory diagnosis: the whole truth, so far

Coronavirus disease 2019 (COVID-19) is the most recent worldwide biological threat to humans worldwide with a severe impact in all areas of human development particularly health, economy, and mobility, caused by a virus belonging to the Coronaviridae family (SARS-CoV-2). Currently, the definite diagnosis of COVID-19 is based on the viral isolation or positive result of polymerase chain reaction (PCR) performed from sputum, nasal swab, or throat swab, although the virus has also been detected in blood and stool. Biological samples collection is performed based on the existing guidelines and PCR protocols had to be adapted. Both sampling and PCR must be performed by specialized professionals in order to avoid false negatives which have been reported in several published papers. Furthermore, considering the limitations of molecular tools such as highly skilled professionals, infrastructure limitations, and supply shortages, rapid diagnostic tests have also been developed based on the detection of viral components (Direct; antigen detection) and in the host immune response (Indirect; antibody detection). Titers of SARS‐CoV‐2 antibodies may be used as an indicator of COVID‐19 prognosis and to discriminate asymptomatic carriers which allows the establishment of the COVID-19 spectrum; however, the persistence, reduction, and duration of SARS‐CoV‐2 immunity antibodies require further investigation. In a period of a pandemic without a vaccine or specific medications to stop the virus progression, testing is the most important task to perform in order to identify and isolate infected persons, even if they don’t present symptoms.