Assessment of Anti-spike and Neutralizing Antibody Response Against SARS-CoV-2 after Covishield and CovaxinTM Vaccination

A BSTRACT Introduction: This study was conducted to determine total and neutralizing antibody (nAb) titer in individuals at an interval of 2 and 6 months after primary vaccination and after 1 month after administration of booster dose. Materials and Methods: A serum sample was collected from 72 volunteers who were vaccinated with either the Covishield or CovaxinTM vaccine for quantitative estimation of human anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike immunoglobulin G (IgG) antibodies and nAb. nAb against SARS-CoV-2 was detected by GenScript (New Jersey, USA) and was quantitatively estimated by in-house developed enzyme-linked immunosorbent assay (ELISA). Results: Out of 72 study participants, 62.5% and 37.5% were male and female, respectively, and were in the age group of 21–83 years. About 94.44% of study volunteers were vaccinated with the Covishield TM vaccine. Diabetes mellitus and hypertension were observed in 7.5% of volunteers. The average time interval between two doses of study vaccination was 37 days. Sixty-seven (93.18%), 50 (69.3%), and 69 (96.8%) ( N = 72) volunteers elicited good nAb response at the end of 2 months, 6 months, and 1 month post-booster dose vaccination, respectively. Conclusion: Rapid nAb reaction to Spike protein development correlates with viral immunity for Covishield vaccine recipients. Due to the availability of limited data for the Covaxin TM vaccine, we are unable to compare the effectiveness of the two vaccinations, and we are also unable to analyze the vaccine’s efficacy.