ABSTRACT
Background and AimsThere is limited data available on longitudinal humoral antibody dynamics following two doses of ChAdOx1-nCOV (CovishieldTM) and BBV-152 (CovaxinTM) vaccine against SARS-CoV-2 among Indians. MethodsWe conducted a 6-month longitudinal study in vaccinated healthcare workers by serially measuring quantitative anti-spike antibody at 3-weeks, 3-months and 6- months after the completion of second dose. Geometric mean titer (GMT) and linear mixed models were used to assess the dynamics of antibody levels at 6 months. ResultsOf the 481 participants, GMT of anti-spike antibody decreased by 56% at 6- months regardless of demographics and comorbidities in 360 SARS-CoV-2 naive individuals, significantly in hypertensives. Participants with past infection had significantly higher GMT at all time points compared to naive individuals. Among SARS-CoV-2 naive cohorts, a significantly higher GMT was noted amongst the Covishield recipients at all time points, but there was a 44% decline in GMT at 6- month compared to peak titer period. Decline in GMT was insignificant (8%) in Covaxin recipients at 6-month despite a lower GMT at all time points vs. Covishield. There was 5.6-fold decrease in seropositivity rate at 6-month with both vaccines. Participants with type 2 diabetes mellitus have a lower seropositivity rate at all the time points. While seropositivity rate was significantly higher with Covishield vs. Covaxin at all time points except at 6-month where Covaxin recipients had a higher seropositivity, although no difference in seropositivity was noted in propensity-matched analysis. ConclusionsThere is waning humoral antibody response following two doses of either vaccine at six months. HighlightsO_LIWe assessed humoral antibody dynamics following two doses of the two vaccines used in India until 6 months. C_LIO_LIOur study of 481 health care workers showed a significant decrease in the anti-spike antibody at 6-months. C_LIO_LIReduction in antibody was regardless of demographics, comorbidities and the vaccine type. C_LIO_LIT2DM cohorts had lowest seropositivity, while hypertensive had significant antibody decline at 6-month. C_LI
ABSTRACT
BackgroundWe 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). MethodA 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) naive 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. ResultsAmong 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 naive 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 naive cohorts, sex, presence of comorbidities, and vaccine type were independent predictors of antibody positivity rate in multiple logistic regression analysis. ConclusionsBoth 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. HighlightsO_LIThis study evaluated the humoral antibody response after 2 doses of SARS-CoV-2 vaccine Covishield and Covaxin in Indian health-care workers. C_LIO_LICombined results of both vaccines showed 95% seropositivity to anti-spike antibody, 21-36 days after the second completed dose. C_LIO_LISeropositivity rates were higher in Covishield recipients compared to Covaxin in the propensity-matched analysis of SARS-CoV-2 naive cohorts. C_LIO_LIGender, presence of comorbidities and the type of vaccine received were independent predictors of antibody response after the second dose. C_LI
