IgG Antibody Seroprevalence Post Covishield Vaccination in Western Uttar Pradesh: A Hospital Based Study

Background: Covid-19, a zoonotic disease caused by Severe Acute Respiratory Syndrome Coronavirus - 2 (SARSCov-2) has emerged as a worldwide infection and has been declared pandemic since March, 2020, by WHO. This has brought about tremendous burden on the health care system of not only the developing or the third world countries but also that of prosperous counties of the world. The recent Covid-19 pandemic has pushed the worldwide scientific and medical community to find a solution with the help of vaccines to control SARS-CoV-2 pandemic. An effective vaccine is one which leads to synthesis of IgG antibodies against SARS-CoV-2, thus aiding the control and decline of the pandemic.

Aim: This study aims to evaluate the antibody titres post 1st dose and post 2nd dose Covishield vaccination and reveals the safety and efficacy of ChAdOx1 nCoV-19(Recombinant) Covishield vaccine.

Methodology: The levels of IgG antibodies were estimated in 215 subjects (both normal subjects and Covid-19 positive subjects) using Enzyme Linked Immunosorbent Assay (ELISA) Technique.

Results: Two hundred & fifteen subjects from Teerthanker Mahaveer Hospital of Moradabad (western Uttar Pradesh) were enrolled for the study. The participants were divided into two different groups. Group I comprised of 215 subjects who received 1st dose of the Covishield vaccine. Group II comprised of 101 subjects who received both the doses of the ChAdOx1 nCoV-19(Recombinant) Covishield vaccine. Levels of IgG were analysed 28 days post 1st dose of ChAdOx1 nCoV-19(Recombinant) Covishield vaccine and post 2nd dose of ChAdOx1 nCoV-19(Recombinant) Covishield vaccination. After testing serologically for neutralising IgG antibodies, the titre was found to be below the threshold level of 1.1 in 67.40% of the subjects in the study group 1, whereas 32.60% (n=70) were found to be in the seroprotective range (i.e IgG titre > 1.1). Out of the total 101 participants who took both the doses, 39 participants (38.6%) were found to be in the seroprotective range (i.e IgG titre > 1.1).

Conclusion: The two doses of Covishield vaccination (4 weeks interval) given to subjects resulted in increase in IgG antibody titre (Neutralising Antibodies) against both spike protein and nucleocapsid protein after 1st dose and 2nd dose and that single dose may suffice for seroprotection in subjects with previous history of COVID-19 who had recovered from the disease.