Antibody Response after Second-dose of ChAdOx1-nCOV (Covishield™^®) and BBV-152 (Covaxin™^®) among Health Care Workers in India: Final Results of Cross-sectional Coronavirus Vaccine-induced Antibody Titre (COVAT) study

Background

We assessed the humoral immune response after the completion of two doses of both ChAdOx1-nCOV (Covishield™) and BBV-152 (Covaxin™) vaccines in Indian health care workers (HCW).

Method

A Pan-India, Cross-sectional, Coronavirus Vaccine-induced Antibody Titre (COVAT) study was conducted that measured SARS-CoV-2 anti-spike binding antibody quantitatively, 21 days or more after the first and second dose of two vaccines in both severe acute respiratory syndrome (SARS-CoV-2) naïve and recovered HCW. Primary aim was to analyze antibody response (seropositivity rate and median [inter-quartile range, IQR] antibody titre) following each dose of both vaccines and its correlation to age, sex, blood group, body mass index (BMI) and comorbidities. Here we report the final results of anti-spike antibody response after the two completed doses.

Results

Among the 515 HCW (305 Male, 210 Female), 95.0% showed seropositivity after two doses of both vaccines. Of the 425 Covishield and 90 Covaxin recipients, 98.1% and 80.0% respectively, showed seropositivity. However, both seropositivity rate and median (IQR) rise in anti-spike antibody was significantly higher in Covishield vs. Covaxin recipient (98.1 vs. 80.0%; 127.0 vs. 53 AU/mL; both p<0.001). This difference persisted in 457 SARS-CoV-2 naïve cohorts and propensity-matched (age, sex and BMI) analysis of 116 cohorts. While no difference was observed in relation to sex, BMI, blood group and any comorbidities; people with age >60 years or those with type 2 diabetes had a significantly lower seropositivity rates. Both vaccine recipients had similar solicited mild to moderate adverse events and none had severe or unsolicited side effects. In SARS-CoV-2 naïve cohorts, sex, presence of comorbidities, and vaccine type were independent predictors of antibody positivity rate in multiple logistic regression analysis.

Conclusions

Both vaccines elicited good immune response after two doses, although seropositivity rates and median anti-spike antibody titre was significantly higher in Covishield compared to Covaxin arm.

Highlights

• This study evaluated the humoral antibody response after 2 doses of SARS-CoV-2 vaccine Covishield™ and Covaxin™ in Indian health-care workers.

• Combined results of both vaccines showed 95% seropositivity to anti-spike antibody, 21-36 days after the second completed dose.

• Seropositivity rates were higher in Covishield recipients compared to Covaxin in the propensity-matched analysis of SARS-CoV-2 naïve cohorts.

• Gender, presence of comorbidities and the type of vaccine received were independent predictors of antibody response after the second dose.