• Julijana Marinac Polyclinic Breyer, Zagreb, Croatia
  • Petra Korac Division of Molecular Biology, Department of Biology, Faculty of Science, University of Zagreb, Zagreb, Croatia
  • Hana Breyer Priselac Polyclinic Breyer, Zagreb, Croatia
Keywords: SARS-CoV-2 immunoassay detection, COVID 19, serological tests


A novel positive-sense RNA virus named Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) was identified in December 2019 in China. It is a systemic disease that includes severe respiratory distress, coronavirus disease 19 (Covid-19). The primary way of transmitting this virus is person-to-person contact via respiratory droplets, but it can also be transmitted by contaminated surfaces. Symptoms range from mild to severe, and the virus spreads quickly. On 11 March 2020 Covid-19 was declared a pandemic by the World Health Organization. The standard way to identify the presence of the virus is to detect its genome using real-time reverse transcriptase polymerase chain reaction (RT-PCR). It can be applied to respiratory tract samples such as nasopharyngeal swabs, sputum and bronchoalveolar lavage. In order to identify contact with the virus and immunological response of the individual, tests based on immunoassays were developed. Many of those tests were produced in short periods of time and they mostly differ on the sample that can be used (serum, plasma or whole blood), complexity and/or expense, and the class of the antibody they detect. The reliability of such tests is of high importance for epidemiological surveys as well as for the development of a vaccine. The aim of this study was to compare three commercially available immunoassay tests. Our results show that different serological tests have different sensitivity and specificity, and that the rapid option, which is the easiest to perform and has the lowest cost, provides the least reliable results.