Abstract

Introduction:
Spike protein antibodies are of prime interest considering their neutralizing capacity for SARS CoV2. Data on seroepidemiology of spike antibody titres in the Indian population is scarce. It's need of the hour to understand the same.
Materials & Method:
We analysed the clinical data of patients who opted for the Quantitative Spike protein IgG antibody test. The data was sub-grouped as per demographic details, vaccination history & history of past COVID infection.
Results:
Overall seropositivity of Spike Antibodies amongst COVAXIN™® users was 84% compared to 97.1% of the users who were vaccinated with COVISHIELD™®. Breakthrough infection cases were 23% post first dose compared to 0.96% of the post-second dose. Median titres in the group with a history of Covid was 5-6-fold higher compared to the group without a history of infection. Individuals vaccinated with COVISHIELD™® produced 2-fold high titres than COVAXIN™® in individuals who did not have a known history of past COVID-19 Infection. No significant difference was observed in titres with an increase in dose gap of COVISHIELD™®. Non vaccinated individuals with past COVID infection less than 6 months ago showed median 2-fold high titres compared to the ones infected earlier. Conclusions: Both COVISHIELD™® and COVAXIN™® have proven to produce seroconversion in almost all the subgroups. Evaluation of cellular immunity and protection by non-spike antibodies needs to be evaluated before drawing more meaningful conclusions. Increasing the gap between two doses did not prove to be of advantage. The need for vaccination can be deferred in COVID infected individuals till 6 months, prioritizing more on the naïve population.

Key words: Cellular Immunity, Humoral Immunity, Immunology, Neutralizing Antibody, Spike Antibody