The study, titled ‘Immunogenicity of SARS-CoV-2 vaccines BBV152 (COVAXIN) and ChAdOx1 nCoV-19 (COVISHIELD) in seronegative and seropositive individuals in India: a multicentre, non-randomized observational study’, compared the immune responses in users for Covishield v Covaxin, it added.

The study involved collaboration between 11 institutes, including at least six from Pune. These six included the Indian Institute of Science Education and Research Pune (IISER), the National Chemical Laboratory (NCL), the National Centre for Cell Science (NCCS), and the Pune Knowledge Cluster.

Covishield was AstraZeneca’s COVID-19 vaccine produced and branded locally by the Adar Poonawalla-led Serum Institute of India (SII) in Pune, while Covaxin was developed and produced by the Hyderabad-based Bharat Biotech.

Here Are the Key Findings of the Study:

1. Covishield’s Robust Immune Responses: The comprehensive study, conducted from June 2021 to January 2022 and encompassing 691 participants aged 18 to 45 from Bangalore and Pune, found that Covishield, which employs a virus vector for spike protein delivery, consistently showed more robust immune responses than Covaxin, an inactivated virus vaccine.

2. Differential Immune Responses: The majority of participants exhibited a near-complete immune response to Covishield, while the response to Covaxin varied, particularly among those vaccinated before the emergence of the Omicron variant.

3. Antibody Levels and T Cells: Covishield induced higher antibody levels in both seronegative (individuals without prior exposure) and seropositive (individuals with prior exposure) subjects, suggesting a more potent and enduring immune response. Additionally, Covishield triggered a higher number of T cells compared to Covaxin, indicating a stronger overall immune response.

4. Protection Against Variants: Covishield consistently demonstrated higher antibody levels against various virus strains, suggesting its potential superior protection against variants such as Omicron.

Significance and Future Implications

“Follow-up studies on vaccine immunology and the analysis of immune protection factors were lacking and there’s a scarcity of comparative studies on these two vaccines. This is one of the very few studies that not only investigates the immune responses of participants after vaccination but also considers their immune history prior to vaccination,” said Dr Mangaiarkarasi Asokan, former programme head, of VISION, and lead author of the study.

“While there was a whole lot of talk going on about which vaccine performed better against the COVID-19 virus, for us in India, only two vaccines were available and the majority of citizens were vaccinated in a phase-wise manner,” said Vineeta Bal, emeritus professor, Biology, IISER Pune on the overall significance of this research.

She added that before this study, there was no comparison data available about the performance and effectiveness of these vaccines. “Some people only had data on Covaxin while others had data on Covishield. For the first time, this study has given us the comparative data for both vaccines,” she added.

Bal also added that they pioneered technology to conduct this study, which will “now be helpful for immunology assessment in future”.

Professor LS Shashidhara, centre director, NCBS, called it a “first-of-its-kind population-level immunological study on vaccines” and noted that it is significant as the virus is “still spreading and evolving”.

“Such studies need serum samples from diverse subjects representing genetic, geoclimatic and nutritional diversity and innovative study design and rigorous statistical methods. No one single organisation can undertake such a study. We are grateful to all our partners and indebted to Hindustan Unilever for its generous funding. Results of this study so far and additional research that we are pursuing will have major inputs for future vaccine strategies as a public health programme,” he added.

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Published: 08 Mar 2024, 07:24 AM IST