Dynamics and Features of the Humoral Response to Covid-19

Abstract

Introduction. This publication describes the continuation of a research to determine the level of specific antibodies in patients in the long term after being suffered from COVID-19. Materials and methods. For this phase of the research, a group of patients who relapsed into a COVID-19 eight months ago (240 days) was examined. The group consists of 42 people. All patients, with no exception, had positive PCR results on COVID-19. Some patients were treated in Hospital № 4 in the infectious department, the other part was treated on an outpatient basis. All patients were relatively divided into two age groups: from 18 to 39 (n = 13) and from 40 to 65 (n = 28). The light form of disease was detected in 29 patients, the moderate form – in 11 and the severe one – in 1 patient. Afterwards the level of the antibodies was controlled on the 60th, 90th, 150th and 240th day after the onset. All patients were tested for antibodies to COVID-19 by enzymelinked immunosorbent assay (ELISA) performed on the equipment: enzyme-linked immunosorbent assay Tecan (Austria); PW 40 Microplate Washer (France). ELISA set for serology COVID-19 test system IgG SARS-CoV-2 VitroTest (Ukraine). Results. According to the first stage of the research, it was recorded that the immune humoral response to Covid-19 was formed in 82 % into the group – in 54 of 66 people. Subsequently, 42 out of 54 individuals with positive antibody levels participated. Analyzing the group of those who have antibodies, we obtained the following results on day 240 from the onset of the disease: IgG levels remain above the threshold level of 80 % (n = 35). It is interesting to note that in 56 % (n = 23) the level of antibodies remains at a very high level. In 20 % (n = 8) into the group, the level of antibodies significantly decreased throughout the research period and became below the threshold by 240 days. Conclusion. Analyzing the data obtained over 8 months (240 days), certain conclusions can be drawn. The maximum level of antibodies was recorded on day 40 from the onset of the disease. It was shown that in the group of patients who had a positive level of specific antibodies to SARS-CoV-2 above the threshold, IgG did not disappear in any patient between 40 and 150 days. However, the downward trend was observed in 20 % of respondents. In this cohort of patients, the antibodies disappeared by day 240. In most patients (80 %) who recover into SARS-CoV-2, IgG levels remain high for at least 240 days.