Omicron-hit may escape reinfection with Delta variant

ICMR conducted a study on 39 individuals, of which 25 had taken both the doses of AstraZeneca COVID-19 vaccine, eight people had taken double dose of Pfizer jab, while six were unvaccinated.

An Indian Council of Medical Research (ICMR) study released on bioRxiv preprint server on Wednesday suggested that immune response induced by Omicron, which is currently the dominant COVID mutant in India, could make re-infection with Delta variant less likely.

The study was conducted on 39 individuals, of which 25 had taken both the doses of AstraZeneca COVID-19 vaccine, eight people had taken double dose of Pfizer jab, while six were unvaccinated. Also, 28 of these 39 were mainly foreign returnees from the UAE, South/West/East Africa, Middle East, the U.S. and the U.K,. and 11 people were their high-risk contacts. All these individuals were infected with the Omicron variant. The study assessed the IgG antibody and Neutralising Antibody (NAb) response in the people with breakthrough and natural COVID-19 infections.

“Our study demonstrated a substantial immune response in the individuals infected with Omicron. The neutralising antibodies could effectively neutralise the Omicron and other variants of concern (VOCs), including the most prevalent Delta variant,” the study stated. The main limitation of this study are 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.