PremiumBharat Biotech’s covid-19 vaccine Covaxin elicits stronger antibody response against the beta and delta variants of SARS CoV2 virus in comparison to post natural infection, showed a study done by Indian Council of Medical Research-National Institute of Virology (NIV).
The study was published in the Journal of Travel Medicine under Oxford Academic on Wednesday. The scientists at ICMR and Bharat Biotech collected blood samples from 20 covid recovered cases and 17 people vaccinated with two doses of Covaxin against the beta and delta variants and compared with the prototype D614G variant (wild).
SARS-CoV-2 variant of delta and beta are a global public health concern due to its impact on existing vaccines. “We assessed the neutralization of sera from covid-19 recovered cases post 5-20 weeks of infection and 28 days after two doses of Covaxin against the variants and compared to prototype B.1 (D614G). Covaxin was found to confer significant protection against both the variants," Pragya D Yadav, scientist at ICMR NIV Pune said.
Over the past several months, several SARS-CoV-2 variants have emerged from various countries worldwide. Among them, the variants of concern (VOC) i.e., alpha (B.1.1.7), beta (B.1.351), gamma (B.1.1.28.1) and delta (B.1.617.2) are serious public health threats because of their association with higher transmissibility and the potential immune escape, the scientists said.
Various reports have been published on the neutralization efficacies with the sera of the currently available covid vaccines against these variants. However, the immune escape of beta variant has been a serious concern for the covid-19 vaccination programme. Another reason of global concern is the recent emergence and detection of the highly transmissible delta variant from India and various other countries.
Covaxin- an inactivated SARS-CoV-2 vaccine was rolled out under the national covid-19 vaccination programme in India. The neutralization potential of the Covaxin has been already studied with the B.1, alpha, zeta, and kappa was found to be effective against these variants.
“The recovered cases in the study were infected with B.1 and B.1.617.1 lineage. Sera of vaccinees and recovered cases had shown a significant reduction in neutralization titer for beta and delta variants in comparison to B.1," said Yadav in the study.
The reduction in neutralization titer of B.1 to beta and delta variants was found to be 3.0 and 2.7 for vaccinated persons and the ratio was 3.3 and 4.6, respectively for recovered cases.
Mutation of delta variant known as 'delta AY.1 and delta AY.2' has been identified from India and other countries which has been a threat to existing vaccine and drugs, the ICMR has noted. “We still do not know how reduced neutralization activity results into reduced vaccine effectiveness; hence vaccine effectiveness studies are absolutely required to fully appreciate the effectiveness of Covaxin against these two variants," said the authors.
The study was approved by the Institutional Biosafety Committee and Institutional Human Ethics Committee of ICMR-NIV, Pune, India under the project comparative assessment of BBV152 vaccine (Covaxin) antibody and antigen-specific responses in immunized population without past covid infection, individuals vaccinated after recovery.
Delta is the most transmissible of the variants identified so far and is spreading rapidly among unvaccinated populations, the World Health Organization (WHO) had earlier said.
First detected in India, the delta variant has been identified in at least 85 countries. Delta is believed to be behind the sudden surge of covid-19 cases during the second covid wave in India.
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