Covishield immune responses against Covid variants higher than Covaxin Study
New Delhi, Jan 7 (PTI) Neutralizing antibody responses against SARS-COV-2 virus and its variants of concern (VoC) were higher among GoviShield recipients, according to a multi-centre study.
A yet-to-be-reviewed study published on the preprint server MedRxiv on Friday found that both vaccines elicited statistically significant antibody levels in seronegative individuals and those who were seropositive or recovered compared to a pre-vaccination baseline. Covid19 infection.
Between June 2021 and January 2022, researchers recruited 691 participants aged 18-45 at four sites in urban and rural Bengaluru and Pune.
Participants received two doses of Covaccine 28 days apart or two doses of CoviShield three months apart.
The Omicron wave in early 2022 overlapped with a second dose of vaccine at two sites and two doses at one site.
Participants were sampled at six time points for antibody analyzes and at four time points for cellular analyses.
Compared to pre-vaccination baseline, both vaccines elicited statistically significant antibody levels in seronegative and seropositive individuals, the researchers found.
Govishield elicited greater magnitude and breadth of immune responses than covaccine in both seronegative individuals and seropositive individuals, indicating the pre-vaccination immune history of the majority of the vaccinated Indian population.
Immunologist Vineetha Pal noted that there is a difference in response to Covid vaccines in young adults if individuals have already been infected with SARS-CoV-2 and recovered (seropositive) and are uninfected.
Paul, of the Indian Institute of Science Education and Research (IISER) in Pune and one of the study authors, “among seronegatives, two doses of Govishield lead to a higher proportion of vaccine recipients compared to covaccine recipients,” Paul told PTI.
“In terms of the decline of immunity over time, individuals vaccinated with GoviShield have a higher proportion of antibodies in their blood for a longer period of time,” he said.
Neither directly examined nor documented protection from Covid-19 in recipients.
“Levels of neutralizing antibodies and T cell responses are, according to different investigators, indirect indicators of protection,” Paul said.
“Interim results so far show that the CowShield vaccine induces strong neutralizing antibodies against the original SARS-CoV2; the covaccine does, but is somewhat less effective,” he added.
“Neutralizing antibodies induced by GoviShield are not as effective against later variants of the virus, such as Delta and Omicron, particularly Omicron, however, they appear to be somewhat better than covaccine recipients,” Paul added.
Previous studies comparing GoviShield and covaccine were limited to addressing antibody responses, particularly in healthcare worker populations immunized before the delta wave.
However, there are limited data on cellular immune responses elicited by these vaccines and no direct head-to-head comparisons or stratification by prevaccination serostatus.
Vaccination after exposure to delta or omicron strains of SARS-CoV-2 can affect the quality, magnitude, and duration of immune responses.
To determine future COVID-19 vaccination policy when pan-coronavirus or sarbecovirus vaccines become available, it is important to take into account the pre-vaccination immune history of the majority of the vaccinated Indian population.
“Some unpublished work from other investigators in India suggests that covaccine increases heterogeneity in GoviShield recipients and vice versa, outperforms homogenous boosting,” Paul added.
