SURVEY OF SEROLOGICAL AND IMMUNOLOGICAL LABORATORY ASSAY TESTS FOR COVID 19

Rajeev Shah*, Reena Mehta, Bhagirath Solanki, A. P. Gupta and Atul Rukadikar

ABSTRACT

While molecular assays (RT- PCR) based viral RNA detection has been widely used in diagnosis of COVID-19, it cannot be used to monitor the progress of the disease stages and cannot be applied to broad identification of past infection and immunity. Serological testing is defined as an analysis of blood serum or plasma and has been operationally expanded to include testing of saliva, sputum, and other biological fluids for the presence of immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies. This test plays an important role in epidemiology and vaccine development, providing an assessment of both short-term (days to weeks) and long-term (years or permanence) trajectories of antibody response, as well as antibody abundance and diversity. IgM first becomes detectable in serum after a few days and lasts a couple of weeks upon infection and is followed by a switch to IgG. Thus, IgM can be an indicator of early stage infection, and IgG can be an indicator of current or prior infection. IgG may also be used to suggest the presence of post-infection immunity. In recent years, the sophistication and sensitivity of immunological assays have increased not only for the detection of antibodies themselves but also for the application of antibodies (primarily monoclonal antibodies) to the detection of pathogen derived antigens

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