Omicron infected have immune response to neutralize Omicron and Delta: ICMR

A study from the Indian Medical Council of Research (ICMR) has demonstrated that individuals infected with Omicron have significant immune response which could neutralise not only the Omicron, but also other variants of concern, including the most prevalent Delta variant.

The study have analyzed the IgG and neutralizing antibodies (NAbs) against B.1, Alpha, Beta, Delta and Omicron variants with the sera of individuals infected with the Omicron variant (B.1.1529 and BA.1). It suggests that the immune response induced by the Omicron could effectively neutralise the Delta variant, making the re-infection with Delta variant less likely and displacing this varaint as the dominant strain. 
This emphasizes the need for the omicron specific vaccine strategy, said the study.

“The GMTs of neutralizing antibodies of ChAdOx1 nCoV-19 breakthrough individuals showed significant fold-reductions compared to B.1 against Alpha (3.23), Beta (2.38), Delta (3.23) and Omicron (4.31) variants respectively. Similarly, BNT162b2 mRNA breakthrough individuals demonstrated significant fold-reduction in GMTs of 1.52 and 7.41 for Delta and Omicron respectively”, said the study.

However, the study has a limitation of 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”, said the study.