Quantification of anti-SARS-CoV-2 antibody after 2nd and 3rd Dose of Vaccination among Health Care Worker

Abstract

IIntroduction: The decision of quick vaccination against covid-19 has possibly minimized the SARS-CoV-2 transmission globally. This effective strategy expedites the development of the immune system among the susceptible. However, frontline healthcare workers (HCWs) are supposed to be more susceptible to infection due to working closely with the patients. It is relatively unknown about the durability of their immune response to covid 19 after receiving a set of covid-19 vaccine doses. Seroprevalence studies that quantify the serum level of e.g. Immunoglobulin G(IgG) and/or Immunoglobulin M (IgM) can be effective in this regard. Therefore, this thesis intended to estimate the prevalence of antibodies and quantify the titer and its durability among vaccinated HCWs. Methods and Materials: Blood samples e.g. heparinized blood specimens (6mL) were collected from 530 healthcare workers from different government and non-government hospitals in Chattagram Metropolitan Area to attain the objectives. The clinical test was performed at the clinical pathology laboratory (CPL) of Chattogram Veterinary and Animal Sciences University (CVASU) within three hours of sample collection. Qualitative ELISA test was executed to determine the presence of antibody (IgG) in the serum sample, and its level was quantified following the method SARS-CoV-2 S1-RBD IgG (DiaSino® Laboratories Co., Ltd. Zhengzhou, China, Ref: DS207704). An Immunochromatographic (ICT) test was also executed to compare with ELISA test results. Association of different variables with the prevalence and titer of antibody was statistically evaluated using STATA-11. Results: antibodies were detected in 99.62% of the study population using the qualitative ELISA test, and 61.13% in ICT test. It was revealed that the prevalence of antibodies increased with the increased number of vaccine doses (p=0.05). Similarly, a statistically significant increase in the titer of antibodies with receiving the higher dose of Covid-19 vaccine was observed in a quantitative ELISA test (p<0.001). Enough antibody titer upto 8 months and onwards after receiving the second dose was found in 71.50 % population. Moreover, the findings revealed that prevalence of antibody development is 1.7 times higher in the symptomatic infected population compared to asymptomatic infected population (OR: 1.7; CI:0.971-3.082; p<0.05). However, a significant association between xii | Page antibody titer development with different potential variables e.g. gender, comorbidities and immunosuppressant were not observed. Conclusion: this thesis emphasizes the role of vaccines in antibody production against SARS-CoV-2 and a robust antibody durability after 2nd dose of vaccination. Therefore, the findings of this thesis would help policy makers to develop a new vaccination strategy regarding the booster dose.