Molecular and serological tests for COVID‑19

Abstract

The outbreak of coronavirus disease 2019 (COVID‑19) has become a global public health problem.There is little known for test utilization and diagnosis. Tests for COVID‑19 include molecular testsand serological tests. Nucleic acid testing is a gold standard, while serological tests are used inseroprevalence. The tests should be selected according to the time course of the virus and serologicalresponse. The targeted genes are several. In our country, real‑time polymerase chain reaction kittargeting RNA‑dependent RNA polymerase gene fragment is being used. Common sample types arenasopharynx and/or oropharynx swabs. Patients with pneumonia sputum, bronchoalveolar lavagefluid, etc., should be tested. The peak concentrations of viral load reach before day 5, and the viruscan be detected until the end of the 1st week after the onset of illness from nasal‑pharynx. Thereare also rapid tests either detect the viral components in nasopharyngeal secretions or antibodies.IgM/IgA and IgG antibody are detectable on day 5 and day 14, respectively, after symptom onset.Enzyme‑linked immunosorbent assay kits based on recombinant nucleocapsid protein and spikeprotein are expected to give more reliable results. Rapid diagnostic tests detecting neither antigennor antibody is the first choice of the World Health Organization for diagnosis but is recommended tobe used for surveillance. Ideal guidance in current circumstances is to confirm cases with availabletests by following national recommendations so that we should take action as soon as possible, giveappropriate therapy, and determine their contacts for infection prevention.