Immune response induced by Omicron effectively neutralise Delta variant: ICMR study

PTI, Jan 26, 2022, 4:07 PM IST

New Delhi: An ICMR study has demonstrated that individuals infected with Omicron have a significant immune response which could neutralize not only the Omicron but also other variants of concern, including the most prevalent Delta variant. It suggests that the immune response induced by the Omicron could effectively neutralize the Delta variant, making the re-infection with Delta variant less likely, thereby displacing the Delta as dominant strain, the study said emphasizing the need for Omicron-specific vaccine strategy. The study was conducted on 39 individuals, of which 25 had taken both the doses of AstraZeneca COVID-19 vaccine, eight people had taken a double dose of Pfizer jab, and six were unvaccinated.

Also, 28 of these 39 were mainly foreign returnees from the UAE, South/West/East Africa, Middle East, the US, and the UK, and 11 people were their high-risk contacts. All these individuals were infected with the Omicron variant. The study assessed the IgG antibody and Neutralizing Antibody (NAb) response in people with breakthrough and natural COVID-19 infections. ”Our study demonstrated substantial immune response in the individuals infected with Omicron. The neutralizing antibodies could effectively neutralize the Omicron and other variants of concern (VOCs), including the most prevalent Delta variant,” the study stated.

The main limitation of this study is lesser participants in the unvaccinated group and the shorter window period post-infection. This could be the important reason for the low immune response specifically in the unvaccinated individuals against Omicron, the scientists stated. The study has been conducted by ICMR scientists, including Pragya D Yadav, Gajanan N Sapkal, Rima R Sahay, and Priya Abraham. It is yet to be peer-reviewed and has been released on the bioRxiv preprint server on January 26.