SARS-CoV-2 IgG antibody response to a viral vector vaccine among health care workers in a tertiary care hospital

Background: The surge of COVID-19 has weighed heavily on health-care systems and hospitals. Health-care workers are at high risk of exposure both in the community and workplace when providing care to patients. Quantitative assays to detect antibodies against SARS COV-2 help to determine individual antibody titer and in longitudinal monitoring of antibody response. The present study was undertaken as there is not much data available regarding the presence of SARS COV-2 antibodies among health care workers in Kerala. The objective was to estimate the IgG antibody response and to find out the associated factors in vaccinated health-care workers. Methods: A cross-sectional study was conducted among 187 vaccinated health- care workers. The blood sample was collected from health care workers and quantitative determination of humoral antibodies (Including IgG) was done by Chemiluminescence immunoassay. The antibody response was correlated with various factors. Analysis was done using the software IBM SPSS Version 25. Results: The seroconversion rate following the Covishield vaccine was found to be 99.47% with mean, median, and standard deviation of antibody titer being 1291.0, 311.40 and 1792.500, respectively. Statistical significance in antibody titer was observed among different categories of health care workers and in those with previous COVID-19 infection. Higher titer was noted within 3 months of vaccination and thereafter waning of titer was seen which was also statistically significant. Conclusion: No correlation was observed with age, gender, co-morbidities, area of work and Body Mass Index (BMI). Vaccination plays a major role in containing the infection. The immune response among vaccinated health-care workers was satisfactory.