In the modern pandemic situation, the main objective is swift and correct diagnosis of SARS-CoV-2. This is essential issue, especially for epidemiological situations in big cities where virus circulates in huge density of people. It should be noted, that antigenic tests of viral proteins are cheaper and faster than molecular diagnosis. Ukraine as a developing country has several test-systems, which were separated into post-Soviet, and EU-trade countries ones. The aim of this investigation is to compare an in-house system (ELISA Vitrotest SARS-CoV-2) and ELISA kit NovaLisa ® SARS-CoV-2. Investigations were carried out on the patients of Kharkiv oblast.
Blood samples positive for COVID-19 were collected from symptomatic patients who came to the emergency room of Medical center «MEDYCHNYI TSENTR ZDOROVIA». Patients were considered positive according to the results of the quantitative reverse transcription-polymerase chain reaction (RT-qPCR). Blood samples were collected in serum collection tubes (BD Vacutainer SST II advance, BD, Plymouth, UK). We evaluated two commercial ELISA kits: ELISA Vitrotest SARS-CoV-2 (IgG, IgM) (Kyiv, Ukraine, hereafter called “Vitrotest”) and NovaLisa® SARS-CoV-2 I (IgG, IgM) (NovaTec®, Dietzenbach, Germany, hereafter called “NovaLisa”). For each ELISA kit, negative and positive controls were assessed and successfully passed. Inconclusive ELISA results were considered as negative for statistical analysis. Significant associations between variables were searched using chi-square test (or Fisher's exact test to prevent overestimation of statistical significance for small data sets) and determination of agreement rate and Cohen's Kappa. The significance threshold was set at $p<0.05$.
Control subjects tested negative for SARS-CoV-2 antibodies with all two systems. Estimated sensitivities varied from 72.5 to 91.5% for IgG detection and from 60.6 to 82.0% for IgM detection. For IgG, Vitrotest and NovaLisa displayed 62-70.5% agreement with other systems. Intermethod agreement for IgM determination was between 30 and 72.5%. Comparison of two systems for SARS-CoV-2 IgG and IgM antibodies showed sensitivity and overall concordance.
The obtained results allow using in-house system to detection of coronaviruses infection SARS-CoV-2 correctly.