Covishield Gives Higher Immune Response Than Covaxin, Finds New Study

The study compared the immune response elicited by Covaxin and Covishield in sero-positive and sero-negative people.

Those vaccinated with Covishield have a higher immune response against COVID-19 than those vaccinated by Covaxin, found a recent study conducted in India.

The study was conducted by researchers in Bengaluru and Pune, notably from CSIR- National Chemical Laboratory (Pune), Christian Medical College, Vellore, and Indian Institute of Science Education and Research (Pune).

The study looks at data collected from participants vaccinated with both Covaxin and Covishield over the course of almost a year.

What did the study find? FIT breaks it down.

Zoom In: “The question that we intended to ask was, how comparable are these two vaccines in terms of their ability to trigger an immune response," says Dr Vineeta Bal, one of the study authors, to FIT.

She explains that the study compared immune response of both the respective vaccines on groups of people that were exposed to the SARS-CoV-2 virus prior to vaccination (Seropositive), with those who were not exposed (seronegative).

Key Points of the Study:

• The study was conducted between 30 June 2021 and 28 January 2022. It began in the midst of the second wave of COVID-19 in the country.

• 691 participants, between the ages of 18-45 were enrolled.

• The participants received two doses of either Covaxin or Covishield.

• The participants were monitored in 4 hospitals across 2 cities (Pune and Bengaluru).

What the study found:

Covishield was found to elicit a higher and longer lasting immune response than Covaxin in both seronegative individuals and seropositive individuals.

"We also found that the concentration of antibodies in such individuals was also higher for Covishield, and they lasted for longer too," says Dr Bal. "This is primarily in the seronegative individuals."

"In the seropositive individuals, while there was some increase in responses, it wasn’t as dramatic as one would see in the unexposed. That is some what similar in the two vaccines."

Dr Vineeta Bal, Immunologist, and researcher at the Indian Institute of Science Education and Research (IISER Pune)

Yes, but the study is still in the pre-print stage, and is yet to be peer-reviewed. Which means its findings are yet to be corroborated.

Moreover, speaking to FIT, Dr Bal said, "our recruitment started during the second wave and date was collected over 6 to 7 months", and so it's difficult to discern how many of the seronegative participants would have been infected with Omicron between their two vaccine shots.

Why it matters: While data on efficacy of COVID-19 vaccines were collected and submitted by vaccine manufacturers to the government, there is very little data comparing the immunogenicity of vaccines, particularly in those that have been exposed to the virus and those that haven't.