Nasopharyngeal (NP) swabs are considered the standard samples for the detection of SARS-CoV-2

Nasopharyngeal (NP) swabs are considered the standard samples for the detection of SARS-CoV-2. strategy to reduce morbidity and mortality. For both epidemiological and clinical purposes, several methodological approaches have been developed. In this article, we will cover the main laboratory methods and protocols that have been used for the control and management of COVID-19. USING LABORATORY DIAGNOSIS TO ENHANCE THE CONTROL OF COVID-19 Reliable laboratory diagnosis represents one of the main tools for the promotion, prevention, and control of infectious diseases 1 . The diagnostic methods for COVID-19 fall under two main categories: immunological and molecular. Immunological tests can be serological tests that mainly detect antibodies in blood or viral antigens in respiratory secretions, and both can be performed with point-of-care platforms. Regarding molecular tests, they are based on the detection of SARS-CoV-2 RNA mainly in nasopharyngeal samples, which in most cases require adequate laboratory infrastructure. In addition to the cited tests, other laboratory parameters have been used as an aid in the clinical monitoring of patients with COVID-19 2 – Pizotifen malate 4 . SEROLOGICAL TESTS Serological tests are especially important Pizotifen malate for the diagnosis of patients with mild to moderate disease, in the absence of molecular diagnostics 5 . These tests can have several benefits, such as estimating the transmissibility and lethality rates, assessing individual and community immunity, and valuing the need and effectiveness of nonpharmaceutical interventions (e.g., social isolation). Furthermore, the plasma of convalescents with high levels of antibody production could be used as a therapeutic support 6 . Several serological tests based on enzyme-linked immunosorbent assay (ELISA), and lateral flow immunochromatography (LFI) devices have been developed by different companies worldwide. IgM and IgG antibodies detected on ELISA have more than 95% specificity in the diagnosis of COVID-19 (18). High titers of IgG antibodies detected by ELISA demonstrate a positive correlation with neutralizing antibodies 7 . Given their point-of-care characteristics, LFI platforms have been widely used. In general, this method detects IgM and IgG antibodies in approximately 20 minutes, individually or simultaneously. Antibodies to glycoprotein S (spike) are analyzed from blood samples obtained by finger puncture without the need for sophisticated equipment or specialized professionals 8 . However, these tests are purely qualitative and can only indicate the presence or absence of SARS-CoV-2 antibodies 5 . Despite its potential value as a tool for pandemic control, the validation of LFI tests remains challenging 9 . The ability to assess their accuracy (sensitivity and specificity) as well as their ability to monitor immunity over time remains insufficient 10 . Another matter of concern is inappropriate interpretation of the result, such as a false understanding that a positive result indicates immunity against the SARS-CoV-2, whereas a positive result on the serological test indicates that the person has come into contact with the virus and developed antibodies, but it is not clear whether these antibodies will provide protection against a reinfection 11 . Currently, antibody responses against SARS-CoV-2 remain poorly understood, and the clinical usefulness of the serological test is still unclear 12 . Although the detection of IgM and IgG by ELISA is positive even on the fourth day after the onset of symptoms, high levels of these antibodies are produced in the second and third weeks of the disease 5 . From the time of onset, the IgM antibody titer increases; 2 weeks after the onset of symptoms, both IgG and IgM are present and their levels start to decrease after the fourth week. IgM is notoriously nonspecific, and because it takes weeks to develop specific IgG responses, serological detection is unlikely to play an active role in case management, with diagnosis/confirmation of late Tbp cases of COVID-19 or determining the immunity of health professionals being the exceptions 12 . The acute antibody response to SARS-CoV-2 in 285 patients in Chinas Hubei province was detected using a chemiluminescence immunoenzymatic test (CLIA). The result showed that the proportion of patients Pizotifen malate positive for specific IgG reached 100% approximately 17 to 19 days.