A new study by a consortium of 11 institutes, led by scientists from the National Centre for Biological Sciences (NCBS), has found that the Covishield vaccine demonstrated more robust immune responses compared to Covaxin.
The study compared the immunogenicity of Covishield and Covaxin, the two primary COVID-19 vaccines widely used in India.
The findings of the study, which have been published in the journal The Lancet Regional Health Southeast Asia, offer valuable insights into the quality and quantity of immune responses induced by these vaccines against SARS-CoV-2, with significant implications for shaping future vaccination strategies.
The key findings state that Covishield, leveraging a virus vector to deliver the spike protein of the coronavirus, consistently demonstrated a more robust immune response compared to Covaxin, an inactivated virus vaccine.
“Notably, Covishield exhibited a near-complete immune response in the majority of participants, whereas the response to Covaxin was variable, particularly among those inoculated before the emergence of the omicron variant,” states the key findings released by NCBS.
The study, carried out from June 2021 to January 2022, involved assessing 691 participants, aged between 18 and 45 years, from Bengaluru and Pune.
It examined their vaccination records and monitored their immune responses at different intervals, both prior to and following vaccination.
Covishield elicited more T cells indicative of a stronger immune response
Further, according to the key finding, 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.
Covishield elicited a higher number of T cells compared to Covaxin, indicative of a stronger immune response.
According to the findings: “Covishield consistently exhibited higher levels of antibodies against various virus strains compared to Covaxin, suggesting its potential superior protection against variants such as omicron”.
“Follow-up studies on vaccine immunology and the analysis of immune protection factors were lacking and, comparative studies are scarce 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 before vaccination,” said Dr. Mangaiarkarasi Asokan, former program head, VISION (Vaccine Immunology Studies-Indian Outbreak-response Network) and lead author of the study.
Prof. Satyajit Mayor, scientist, NCBS-TIFR, said that this study was done at the height of the Covid pandemic and reflected a collective sentiment to bring evidence-based decision-making to the outcomes of vaccination in the Indian population, using two indigenous vaccines that were rolled out very quickly for the Indian population.
Lessons for future strategies
“The creation of a bio-repository from the 15-month longitudinal study is invaluable. Analysis of the data and exploring the collected bio-resources will inform future immunization strategies, at least for COVID-19. Finally, the outcome of the study where the Covishield vaccine was shown to outperform Covaxin in all respects, should have important implications to strategize future vaccination drives,” Prof. Mayor said.
