A Prospective Study of Seroconversion Post Covishield Vaccination in COVID-19 Warriors

Abstract

Introduction: During the Coronavirus Disease 2019 (COVID19) pandemic in India, two vaccinees were predominantly administered to prevent the spread of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). The first vaccine introduced in India was ChAdOx1-nCOV (Covishield), followed by BBV-152 (Covaxin). In the first phase, Healthcare Workers (HCW) were prioritised for vaccination, given their crucial role in the healthcare system. Aim: To assess the antibody response post Covishield vaccination at specific time intervals in HCWs and to determine the correlation of antibody response with age, gender, comorbidities and blood group. Materials and Methods: This prospective study was conducted at Dr. Balasaheb Vikhe Patil Rural Medical College, Pravara Institute of Medical Sciences, Loni, Maharashtra, India, over a duration of six months from January 2021 to June 2021. A total of 110 vaccinated HCWs who volunteered were included in this study. SARS-CoV-2 antibodies at specific time intervals were assessed using Ortho Clinical Diagnostic’s VITROS 3600 based on the principle of Chemiluminescent Immunosorbent Assay (CLIA). Assessment of anti-SARS-CoV-2 total and IgG antibodies was performed at 15 days, one month, one and a half months, two months, three months, and four months postfirst dose of vaccination, or in other words, 15 days and one month after the 1st dose, and 15 days, one month, two months, and three months post second dose of vaccination. For analysis, Pearson’s correlation and a regression model were performed using GraphPad Prism 8.0.2 version. Results: Fifteen days post second dose, 110 HCWs (100%) and 109 (99.09%) HCWs turned seropositive for total antibodies and IgG antibodies, respectively. It was observed that the majority of participants (33, 30.27%) with peak IgG levels in the medium range were from the age group of 31-40 years. Overall, there was a negative correlation between age and IgG antibody levels for peak IgG values (r-value=-0.224, p-value=0.019). The peak values were achieved in the majority of participants 15 days post second dose (53.6%). The difference in antibody levels based on gender was not significant (Chi-square value=3.387, p-value=0.184). No significant difference in SARS-CoV-2 IgG levels was observed between participants with co-morbidities and those without co-morbidities. Participants who developed SARS-CoV-2 infection during the study period exhibited robust antibody responses after vaccination. Conclusion: These findings help elucidate Covishield vaccinespecific antibody responses in vaccinees of different age groups, genders, blood groups, and with co-morbid conditions. The vaccine has substantially reduced the burden of disease by preventing serious illness in vaccinated HCWs during the second wave of the COVID-19 pandemic.