Reliability and usefulness of a rapid IgM‐IgG antibody test for the diagnosis of SARS-CoV-2 infection: a preliminary report

Large-scale screening programs using antibody tests are currently under evaluation by different governments. Recently, a test for the rapid detection of combined IgG and IgM antibodies to SARS-CoV-2 in human blood, serum/plasma has become available.6 As soon as the kits were commercially available, we assessed the reliability and usefulness of the 2019-nCoV IgG/IgM Antibody Rapid Test Kit (Beijing Diagreat Biotechnologies Co., Ltd) in patients with confirmed Covid 19 and in a small sample of patients with suspected disease, who were screened to be admitted to either a Covid 19 Unit or to a non Covid 19 ward. We enrolled a total of 30 patients admitted to the Infectious Disease Covid 19 Unit or to the Pneumology Unit (Azienda UO Policlinico-San Marco, Catania) and 7 healthy controls. The study population was divided in three groups: In the group with suspected Covid 19, which was anyway very small, we found mainly a consistency between negative molecular and negative antibody test. However, the antibody test was performed earlier, compared to the group with confirmed disease (median 9 days vs 18 days) and this may have biased these results, so that we will further test these patients. To our opinion this antibody test is quite reliable and useful, since it has the advantage to be a point-of-care test that gives a response within minutes. In those patients presenting with a discrepancy between the clinical/radiological feature and the molecular test, the rapid antibody detection might be an additional element helping the clinician to make a correct diagnosis. This is true, as long as the test is not performed within the first days of symptoms onset. Indeed, further studies are granted to investigate both the diagnostic and the screening value of this test.