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
ABSTRACT
BackgroundTwo vaccines are currently being administered in India to prevent the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We assessed the humoral immune response after the first dose of two vaccines ChAdOx1-nCOV (Covishield) and BBV-152 (Covaxin) in Indian health care workers (HCW). MethodsThis ongoing, Pan-India, Cross-sectional, Coronavirus Vaccine-induced Antibody Titre (COVAT) study is being conducted amongst HCW, with or without past history of SARS-CoV-2 infection. SARS-CoV-2 anti-spike binding antibody is being assessed quantitatively at four timepoints between 21 days or more after the first dose to 6 months after the second dose. Primary aim is to analyze antibody response following each dose of both vaccines and its correlation to age, sex, body mass index (BMI) and comorbidities. Here we report the preliminary results of anti-spike antibody response after the first dose. ResultsAmongst the 552 HCW (325 Male, 227 Female), 456 and 96 received first dose of Covishield and Covaxin respectively. Overall, 79.3% showed seropositivity after the first dose. Responder rate and median (IQR) rise in anti-spike antibody was significantly higher in Covishield vs. Covaxin recipient (86.8 vs. 43.8%; 61.5 vs. 6 AU/ml; both p<0.001). This difference persisted in propensity-matched (age, sex and BMI) analysis in 172 subjects. No difference was observed with age, gender and BMI. History of hypertension had lower responder rate (65.7 vs. 82.3%, p=0.001). Covishield recipient had more adverse event vs. Covaxin arm (46.7 vs. 31.2%, p=0.006). Presence of comorbidities, past SARS-CoV-2 infection and vaccine types used were independent predictors for seropositivity after the first dose, in multiple logistic regression analysis. ConclusionsWhile both vaccines elicited immune response, seropositivity rates to anti-spike antibody were significantly higher in Covishield recipient compared to Covaxin after the first dose. Ongoing COVAT study will further enlighten the immune response between two vaccines after the second dose. HighlightsO_LIThis study evaluated the humoral antibody response of two SARS-CoV-2 vaccines Covishield and Covaxin in Indian health-care workers. C_LIO_LIBoth vaccines showed seropositivity to anti-spike antibody, 21 days or more after the first dose. C_LIO_LIResponder rates were higher in Covishield recipient compared to Covaxin in propensity-matched cohorts. C_LIO_LIPast SARS-CoV-2 infection, presence of comorbidities and vaccine type received were independent predictors of antibody response after the first dose. C_LI
ABSTRACT
In this work we construct a mathematical model for the transmission and spread of coronavirus disease 2019 or COVID-19. Our model features delay terms to account for (a) the time lapse or latency period between contracting the disease and displaying symptoms, and (b) the time lag in testing patients for the virus due to the limited numbers of testing facilities currently available. We find that the delay introduces a significant disparity between the actual and reported time-trajectories of cases in a particular region. Specifically, the reported case histories lag the actual histories by a few days. Hence, to minimize the spread of the disease, lockdowns and similarly drastic social isolation measures need to be imposed some time before the reported figures are approaching their peak values. We then account for the social reality that lockdowns can only be of a limited duration in view of practical considerations. We find that the most effective interval for imposing such a limited-time lockdown is one where the midpoint of the lockdown period coincides with the actual peak of the spread of the disease in the absence of the lockdown. We further show that the true effectivity of imposing a lockdown may be misrepresented and grossly underestimated by the reported case trajectories in the days following the action.
