Immunogenicity of two COVID-19 vaccines used in India: An observational cohort study in health care workers from a tertiary care hospital

Humoral and cellular immune response to AZD1222 /Covishield and BV152/Covaxin COVID-19 vaccines among adults in India

Several COVID-19 vaccines were developed using different approaches to prevent both symptomatic COVID-19 cases and fatalities. The adults were vaccinated with two doses of AZD1222/Covishield (n = 77) [manufactured by Serum Institute of India Pvt Ltd] vaccine and BV152/Covaxin (n = 99) [manufactured by Bharat Biotech] vaccine. They were assessed for immune response at pre-vaccination, 1 month post first and 6 months post second dose for anti-SARS-CoV-2 IgG antibody, surrogate neutralizing antibody (NAbs), immune phenotypes, antigen specific NK, B and T cell response, their effector functionality by ELISPOT and plasma cytokine profile. Both vaccines elicited enhanced IgG antibody and Nab levels compared to the baseline. BV152/Covaxin, the whole virus inactivated vaccine exhibited higher IgG (70% vs 100%), Nab (90% vs 100%), and robust T cell (31% vs 96%) responses at 6 months post second dose compared to 1 month post first dose justifying the utility of the second dose. Detection of SARS-CoV-2 WV and S1 specific CD4+ central T cell memory response in AZD1222/Covishield vaccinee at 6 months post second dose and higher CD4+ and CD8+ naïve and central memory T cell response in BV152/Covaxin vaccinee at 1 month post first dose indicated the involvement of memory T cells. Persistent IgG and NAb responses along with IgG+B and IgG+memory B cells in AZD1222/Covishield recipients at 6 months post second dose indicated sustained immune memory response. Continued heightened IFN-γ secreting T cell response (ELISPOT) displayed by both the vaccine platforms could serve as a co correlate of protection, further to evaluation in follow up studies. Overall, our data suggest that coordinated functions of humoral and cellular branches of adaptive immunity may pave ways toward protective immunity against COVID-19.

Neutralizing Antibodies against 10 SARS-CoV-2 Variants at Two Years Post-COVISHIELD Vaccination with Special Reference to Omicron Subvariants and Booster Administration

To study the durability of neutralizing antibodies (NAbs) against ten SARS-CoV-2 variants among COVISHIELD vaccine recipients from Pune, India, 184 vaccinee samples with (pre-positives) or without (pre-negatives) prior antibody positivity were evaluated. To estimate NAb levels, a validated ten-plex MSD ACE2 neutralization assay was used. NAbs against Alpha, Beta, Delta, and Omicron/subvariants were assessed at 1 month (PD2-1) and 6 months (PD2-6) post-vaccination, post-booster dose, and 2 years (2Y) post-vaccination. In pre-negatives, the seropositivity declined from PD2-1 to PD2-6 for all variants (Omicron variants: 14-54% to 0%; non-Omicron variants: 66-100% to 8-44%). In pre-positives, the decline in seropositivity from PD2-1 to PD2-6 was seen only for Omicron variants (14-39%). At PD2-6, a significant reduction in NAb levels was observed in all vaccinees against all the variants. Irrespective of prior exposure, the diminished anti-variant antibody levels at PD2-6 increased significantly following the administration of the booster. In conclusion, the COVISHIELD vaccine booster dose did provide cross-neutralizing antibodies against broad-range SARS-CoV-2 variants with improved durability up to [16 (15-18)] months post-booster dose and two years post-vaccination.

IgG responses against SARS-CoV-2 vaccines AZD1222 and BBV-152 and breakthrough infections among health care workers in southern India

IgG antibodies elicited in response to SARS-CoV-2 are critical in determining the protection achieved through vaccination. The present longitudinal study aims to assess the immune response generated through AZD1222 & BBV-152 vaccination among health care workers (HCWs) in a selected hospital. Serum IgG levels were measured approximately at 1.5 months and 6 months after the first and second vaccination. The final assessment was done 12 months after the first vaccination to analyse the sustained antibody levels. Results showed a progressive increase in antibody titres as a function of time. 26 HCWs in all had SARS-CoV-2 breakthrough infection, but their antibody titres were not significantly higher compared to COVID-19 naïve individuals. However, a comparative analysis showed considerably higher antibody titre in those who received the AZD1222 vaccine among this cohort. AZD1222 vaccination was significantly associated with seropositivity in the first and second assessments. Female HCWs showed significantly higher seropositivity, and participants above 60 years showed considerably reduced antibody titre in the first assessment. However, the final assessment showed no association with these variables, with 97.1 % of participants reporting to be seropositive. The results indicate good antibody response and potential protection against SARS CoV-2.

Cell-Mediated Immunity (CMI) for SARS-CoV-2 Infection Among the General Population of North India: A Cross-Sectional Analysis From a Sub-sample of a Large Sero-Epidemiological Study

Background Cell-mediated immunity (CMI), or specifically T-cell-mediated immunity, is proven to remain largely preserved against the variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), including Omicron. The persistence of cell-mediated immune response in individuals longitudinally followed up for an extended period remains largely unelucidated. To address this, the current study was planned to study whether the effect of cell-mediated immunity persists after an extended period of convalescence or vaccination. Methods Whole blood specimens of 150 selected participants were collected and tested for Anti-SARS-CoV-2 Interferon-gamma (IFN-γ) response. Ex vivo SARS-CoV-2-specific interferon-gamma Enzyme-linked Immunospot (IFN-γ ELISpot) assay was carried out to determine the levels of virus-specific IFN-γ producing cells in individual samples. Findings Out of all the samples tested for anti-SARS-CoV-2 T-cell-mediated IFN-γ response, 78.4% of samples were positive. The median (interquartile range) spots forming units (SFU) per million levels of SARS-CoV-2-specific IFN-γ producing cells of the vaccinated and diagnosed participants was 336 (138-474) while those who were vaccinated but did not have the disease diagnosis was 18 (0-102); the difference between the groups was statistically significant. Since almost all the participants were vaccinated, a similar pattern of significance was observed when the diagnosed and the never-diagnosed participants were compared, irrespective of their vaccination status. Interpretations Cell-mediated immunity against SARS-CoV-2 persisted, irrespective of age and sex of the participant, for more than six months of previous exposure. Participants who had a history of diagnosed COVID-19 infection had better T-cell response compared to those who had never been diagnosed, in spite of being vaccinated.

A Phase 3, randomized, non-inferiority study of a heterologous booster dose of SARS CoV-2 recombinant spike protein vaccine in adults

Due to waning immunity following primary immunization with COVID-19 vaccines, booster doses may be required. The present study assessed a heterologous booster of SII-NVX-CoV2373 (spike protein vaccine) in adults primed with viral vector and inactivated vaccines. In this Phase 3, observer-blind, randomized, active controlled study, a total of 372 adults primed with two doses of ChAdOx1 nCoV-19 (n = 186) or BBV152 (n = 186) at least six months ago, were randomized to receive a booster of SII-NVX-CoV2373 or control vaccine (homologous booster of ChAdOx1 nCoV-19 or BBV152). Anti-S IgG and neutralizing antibodies (nAbs) were assessed at days 1, 29, and 181. Non-inferiority (NI) of SII-NVX-CoV2373 to the control vaccine was assessed based on the ratio of geometric mean ELISA units (GMEU) of anti-S IgG and geometric mean titers (GMT) of nAbs (NI margin > 0.67) as well as seroresponse (≥ 2 fold-rise in titers) (NI margin -10%) at day 29. Safety was assessed throughout the study period. In both the ChAdOx1 nCoV-19 prime and BBV152 prime cohorts, 186 participants each received the study vaccines. In the ChAdOx1 nCoV-19 prime cohort, the GMEU ratio was 2.05 (95% CI 1.73, 2.43) and the GMT ratio was 1.89 (95% CI 1.55, 2.32) whereas the difference in the proportion of seroresponse was 49.32% (95% CI 36.49, 60.45) for anti-S IgG and 15% (95% CI 5.65, 25.05) for nAbs on day 29. In the BBV152 prime cohort, the GMEU ratio was 5.12 (95% CI 4.20, 6.24) and the GMT ratio was 4.80 (95% CI 3.76, 6.12) whereas the difference in the proportion of seroresponse was 74.08% (95% CI 63.24, 82.17) for anti-S IgG and 24.71% (95% CI 16.26, 34.62) for nAbs on day 29. The non-inferiority of SII-NVX-CoV2373 booster to the control vaccine for each prime cohort was met. SII-NVX-CoV2373 booster showed significantly higher immune responses than BBV152 homologous booster. On day 181, seroresponse rates were ≥ 70% in all the groups for both nAbs and anti-S IgG. Solicited adverse events reported were transient and mostly mild in severity in all the groups. No causally related SAE was reported. SII-NVX-CoV2373 as a heterologous booster induced non-inferior immune responses as compared to homologous boosters in adults primed with ChAdOx1 nCoV-19 and BBV152. SII-NVX-CoV2373 showed a numerically higher boosting effect than homologous boosters. The vaccine was also safe and well tolerated.

Estimation of SARS-CoV-2 IgG Antibodies in Healthcare Worker-Administered Covishield and Covaxin Vaccines at a Tertiary Care Hospital in Jharkhand, India

Introduction To mitigate the impact of the COVID-19 pandemic caused by the SARS-CoV-2 virus, global distribution of vaccines such as Covishield and Covaxin has been undertaken. This research aimed to assess the responses and potential differences between these vaccines by examining the presence and levels of SARS-CoV-2 IgG antibodies in healthcare professionals who received them. Methodology A comprehensive cross-sectional study was conducted at a tertiary care facility in Ranchi involving 227 healthcare professionals who had completed both doses of either Covishield or Covaxin. Blood samples were collected and subjected to chemiluminescence immunoassay analysis to measure IgG antibodies. Demographic data, immunization records, and previous COVID-19 infections were recorded. Statistical analyses, including analysis of variance (ANOVA), linear regression, and independent sample t-tests were performed. Results Antibody titers exhibited variability, potentially influenced by factors. There was no difference in antibody titers between recipients of Covishield and Covaxin vaccines. Linear regression analysis revealed a correlation between antibody levels and the number of days after vaccination. Factors such as age, gender, blood group, and prior COVID-19 infections did not significantly impact antibody titers. Conclusions This study contributes to responses elicited by Covishield and Covaxin vaccines among healthcare workers. The results highlight that Covishield showed a higher mean titer value than Covaxin, which is not statistically significant. The overall model showed statistically significant results indicating age, type of vaccine, number of days after vaccination, blood group, and previous history of COVID-19 infection collectively influenced the CoV-2 IgG titer values. The findings indicate that age, number of days after vaccination, and prior history of COVID-19 infection have substantial relationships with the CoV-2 IgG titer, but sex, vaccine type, and blood group show lesser, nonsignificant associations.

Polyfunctional CD4 T-cells correlating with neutralising antibody is a hallmark of COVISHIELDTM and COVAXIN® induced immunity in COVID-19 exposed Indians

Detailed characterisation of immune responses induced by COVID-19 vaccines rolled out in India: COVISHIELDTM (CS) and COVAXIN® (CO) in a pre-exposed population is only recently being discovered. We addressed this issue in subjects who received their primary series of vaccination between November 2021 and January 2022. Both vaccines are capable of strongly boosting Wuhan Spike-specific neutralising antibody, polyfunctional Th1 cytokine producing CD4+ T-cells and single IFN-γ + CD8+ T-cells. Consistent with inherent differences in vaccine platform, the vector-based CS vaccine-induced immunity was of greater magnitude, breadth, targeting Delta and Omicron variants compared to the whole-virion inactivated vaccine CO, with CS vaccinees showing persistent CD8+ T-cells responses until 3 months post primary vaccination. This study provides detailed evidence on the magnitude and quality of CS and CO vaccine induced responses in subjects with pre-existing SARS-CoV-2 immunity in India, thereby mitigating vaccine hesitancy arguments in such a population, which remains a global health challenge.

P. G, Goyal D, Malhotra RK, Mishra P, Shukla M, Gupta A, Kohli V, Bundela N, Batra V, Bansal A, Yadav R, Yusuf J, Mukhopadhyay S. Impact of COVID-19 vaccination on mortality after acute myocardial infarction

BACKGROUND

COVID-19 vaccines are highly immunogenic but cardiovascular effects of these vaccines have not been properly elucidated.

OBJECTIVES

To determine impact of COVID-19 vaccination on mortality following acute myocardial infarction (AMI).

METHODS

This was a single center retrospective observation study among patients with AMI enrolled in the the North India ST-Elevation Myocardial Infarction (NORIN-STEMI) registry. In all the enrolled patients, data regarding patient's vaccination status including details on type of vaccine, date of vaccination and adverse effects were obtained. All enrolled subjects were followed up for a period of six months. The primary outcome of the study was all-cause mortality both at one month and at six months of follow-up. Propensity-weighted score logistic regression model using inverse probability of treatment weighting was used to determine the impact of vaccination status on all-cause mortality.

RESULTS

A total of 1578 subjects were enrolled in the study of whom 1086(68.8%) were vaccinated against COVID-19 while 492(31.2%) were unvaccinated. Analysis of the temporal trends of occurrence of AMI post vaccination did not show a specific clustering of AMI at any particular time. On 30-day follow-up, all-cause mortality occurred in 201(12.7%) patients with adjusted odds of mortality being significantly lower in vaccinated group (adjusted odds ratio[aOR]: 0.58, 95% CI: 0.47-0.71). Similarly, at six months of follow-up, vaccinated AMI group had lower odds of mortality(aOR: 0.54, 95% CI: 0.44 to 0.65) as compared to non-vaccinated group.

CONCLUSIONS

COVID-19 vaccines have shown to decrease all-cause mortality at 30 days and six months following AMI.

Variable neutralizing antibody responses to 10 SARS-CoV-2 variants in natural infection with wild- type (B.1) virus, Kappa (B.1.617.1), and Delta (B.1.617.2) variants and COVISHIELD vaccine immunization in India: utility of the MSD platform

For the efficacy of COVID-19 vaccines, emergence of variants accumulating immune-escape mutations remains a major concern. We analyzed the anti-variant (n = 10) neutralization activity of sera from COVID-19 patients infected with Wuhan (B.1), Kappa, and Delta variants and COVISHIELD vaccine recipients with (prepositives) or without (prenegatives) prior antibody positivity using V- PLEX ACE2 Neutralization Kit from MSD. MSD and PRNT₅₀ correlated well (r = 0.76-0.83, p < 0.0001). Despite the least antibody positivity in Kappa patients, anti-variant neutralizing antibody (Nab) levels in the responders were comparable with Delta patients. Vaccinees sampled at 1 month (PD2-1) and 6 months (PD2-6) post-second dose showed the highest seropositivity and Nab levels against the Wuhan strain. At PD2-1, the responder rate was variant-dependent and 100% respectively in prenegatives and prepositives. Nab levels against B.1.135.1, B.1.620, B.1.1.7+E484K (both groups), AY.2 (prenegatives), and B.1.618 (prepositives) were lower than that of Wuhan. At PD2-6, positivity decreased to 15.6%-68.8% in the prenegatives; 3.5%-10.7% of prepositives turned negative for the same four variants. As against the decline in Nab levels in 9/10 variants (prenegatives), a further reduction was seen against the same four variants in the prepositives. These variants possess immune-evasion-associated mutations in the RBD/S region. In conclusion, our data show that the Nab response of patients to multiple variants depends on the infecting variant. We confirm superiority of hybrid immunity in neutralizing multiple variants. Depending on the infecting variant pre- or postvaccination, immune response to different vaccines in different populations will vary and impact protection against emerging variants. The MSD platform provides an excellent alternative to live virus/pseudovirus neutralization tests.

Effectiveness and Safety of Inactivated SARS-CoV-2 Vaccine (BBIBP-CorV) among Healthcare Workers: A Seven-Month Follow-Up Study at Fifteen Central Hospitals

BACKGROUND

During a pandemic, healthcare workers are at high risk of contracting COVID-19. To protect these important individuals, it is highly recommended that they receive the COVID-19 vaccine. Our study focused on evaluating the safety and efficacy of Egypt's first approved vaccine, the Sinopharm vaccine (BBIBP-CorV), and comparing these findings with other vaccines.

METHODS

An observational study was conducted in fifteen triage and isolation hospitals, from the 1st of March until the end of September 2021. The study included fully vaccinated and unvaccinated participants, and we measured vaccine effectiveness (using 1-aHR), the incidence rate of severely to critically ill hospitalized cases, COVID-19-related work absenteeism, and the safety of the vaccine as outcomes.

RESULTS

Of the 1364 healthcare workers who were interviewed, 1228 agreed to participate. After taking the hazard ratio into account, the vaccine effectiveness was found to be 67% (95% CI, 80-43%) for symptomatic PCR-confirmed cases. The incidence rate ratio for hospitalization was 0.45 (95% CI, 0.15-1.31) in the vaccinated group compared to the unvaccinated group, and there was a significant reduction in absenteeism among the vaccinated group (p < 0.007). Most adverse events were mild and well tolerated. Vaccinated pregnant and lactating mothers did not experience any sentinel adverse events.

CONCLUSION

Our study found that the BBIBP-CorV vaccine was effective in protecting healthcare workers from COVID-19.

Effectiveness of Covid-19 vaccines (CovishieldTM and Covaxin ®) in healthcare workers in Mumbai, India: A retrospective cohort analysis

BACKGROUND

India started its vaccination programme for Coronavirus-19 infection (COVID-19) on 16 January 2021 with CovishieldTM (Oxford/Astra Zeneca vaccine manufactured by Serum Institute of India) and Covaxin ® (Bharat Biotech, India). We designed the present study to study the effectiveness of vaccines for COVID-19 in prevention of breakthrough infections and severe symptomatic cases among health care workers in a real-life scenario in Mumbai, India. Furthermore, we also wanted to study the factors associated with this effectiveness.

METHODS

This is cohort analysis of secondary data of 2762 individuals working in a tertiary health care setting in Mumbai, India (16 January 2021 to 16 October 2021). Vaccination records of all groups of health care staff (including the date of vaccination, type of vaccine taken, and date of positivity for COVID-19) were maintained at the hospital. The staff were tested for COVID-19 at least once a week and when symptomatic. The observation time for everyone was divided into unvaccinated, partially vaccinated (14 days after the first dose); and fully vaccinated (14 days after the second dose). If the individual was found to be positive, the day of positivity was considered the 'day of the event' for that individual. We combined unvaccinated/partially vaccinated into one group and completely vaccinated in the other group. We estimated hazard ratios (HR) and their 95% confidence intervals. The vaccine effectiveness (VE) was assessed as (1-HR)*100.

RESULTS

The mean age (SD) of the study participants was 32.3 (8.3) years; majority of these individuals had taken Covishield TM (99.0%) and only 0.9% (n = 27) had taken Covaxin ®. The incidence rate in the overall population was 0.067/100 person-days (PD). The incidence rate was significantly higher in the unvaccinated/partially vaccinated group compared with the fully vaccinated group (0.0989 / 100 PD vs 0.0403/100 PD; p < 0.001). The adjusted HR (aHR) in the fully vaccinated group compared with the unvaccinated/partially vaccinated group in the complete cohort was 0.30 (95% CI: 0.23, 0.39). Thus, the vaccine effectiveness (VE) for full vaccination was 70% (95% CI: 61%, 77%). It remained the same in the Covishield TM only cohort. The VE in completely vaccinated and with a history of previous infection was 88% (95% CI: 80%, 93%). Only 11 health care workers required hospitalization over the entire observation period; the incidence rate in our cohort was 0.0016 / 100 PD. None of the HCWs reported any severe adverse events after vaccination.

CONCLUSIONS

In this real-world scenario, we did find that complete vaccination reduced the rate of infection, particularly severe infection in health care personnel even during the severe delta wave in the country. Even among those infected, the hospitalisation rates were very low, and none died. We did not record any major side effects of vaccination in these personnel. Previous infection with COVID-19 and complete vaccination had a significantly higher effectiveness in prevention of infection.