ABSTRACT
The coronavirus disease-2019 (COVID-19) has become a global cause of death/injury, particularly for those with limited access to vaccination programs and healthcare systems. The risk of re-infection is not negligible due to the emergence of new variants and the decrease in immunity of those who have recovered COVID-19 before. In this study, it was aimed to show longitudinally the change in antibody levels of patients hospitalized for COVID-19 who had an antibody response in the early stages of their infection and to reveal a response pattern that would help to predict patients whose antibody responses decreased or persisted over time. This observational, single-center study included 38 non-critical patients admitted to COVID-19 wards. Anti-spike-1 IgG levels were investigated by the "enzyme-linked immunosorbent assay (ELISA)" method in two different samples taken at different times in each patient. Two distinct anti-spike-1 IgG antibody response patterns were detected in the study; the first pattern was that with low antibody production at first who had an increase in antibody levels after an average of six months, and the second pattern was that the initially high antibody levels decreased after an average of six months. This paradoxical kinetic may blur physicians' predictions of antibody response. In general, anti-spike-1 antibody levels showed a moderate decrease after six months, but production seems to continue (mean ∆IgG= -0.77; σ= 4; p= 0.24). Higher antibody levels were observed at the beginning in patients with concomitant bacterial pneumonia (mean initial IgG= 7.67; σ= 3.54) (p= 0.03). Although the production of S1-IgG in patients recovered from severe acute respiratory system coronavirus2 (SARS-CoV-2) was modestly reduced compared to the beginning measurements, the production in general persisted during the study period. It appears that IgG responses increase or remain constant in individuals with relatively low IgG index values when controlled after an average of 180 days, while IgG tends to decrease in individuals with high IgG index values.
Subject(s)
COVID-19 , Antibodies, Viral , Antibody Formation , Humans , Immunoglobulin G , SARS-CoV-2 , Spike Glycoprotein, CoronavirusABSTRACT
COVID-19 infection caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) continues to affect people as a global threat, and the number of cases is increasing every day. Healthcare workers who face potential COVID-19 exposure are at high risk of SARS-CoV-2 transmission. Estimating the prevalence of infection among healthcare professionals, determining the related risk factors and applying effective infection control measures are essential for the continuity of the health system. The aim of this study was to investigate the seroprevalence of SARS-CoV-2 among healthcare workers in our hospital who have participated extensively in the monitoring of COVID-19 patients. In the study, the anti-SARS-CoV-2 IgG antibody test results of 774 healthcare workers between March 24, 2020, and September 10, 2020 were analyzed retrospectively. Age, sex, profession, and the status of being diagnosed with COVID-19 before the antibody test were determined for the healthcare workers in the study. When the anti-SARS-CoV-2 IgG antibody results were evaluated, it was determined that 57 healthcare workers were positive, 708 healthcare workers were negative, and 9 healthcare workers were borderline. The seroprevalence among the workers of our hospital was found to be 7.4%. The antibody positivity rate was 75.6% in individuals diagnosed with COVID-19 by SARS-CoV-2 PCR (polymerase chain reaction) and/or thoracic computed tomography and it was found to be 3.5% in individuals without the diagnosis. The semi-quantitative antibody index values of the healthcare workers who were seropositive and diagnosed with COVID-19 before the test (n= 31) and those who did not (n= 26) were statistically compared and a significant difference was found between the two groups (p<0.01). In our study, the highest seropositivity was observed among residents (12.3%) and among nurses (11.1%), respectively. When the seropositivity rates of the residents and the nurses were compared with other occupational groups, the differences were found to be statistically significant (p= 0.04, p= 0.04, respectively). In conclusion, the seroprevalence of SARS-CoV-2 was determined as 7.4% among healthcare workers in a tertiary hospital with high patient admissions during the COVID-19 pandemic. Considering that SARS-CoV-2 seroprevalence was announced as 0.81% in the press release made by the Ministry of Health of Turkey in July 2020, it is seen that the rate of seroprevalence among health care workers is significantly larger than the community. Determination of the seroprevalence in the general population and large-scale studies are needed for risk assessment in healthcare professionals.