BA.2 and BA.5 omicron differ immunologically from both BA.1 omicron and pre-omicron variants

Area of Science:

• Virology
• Immunology
• Epidemiology

Background:

• SARS-CoV-2 Omicron BA.1 is an immune escape variant.
• Omicron BA.2 and BA.5 sub-variants have replaced BA.1 globally.
• These sub-variants possess mutations distinct from BA.1.

Purpose of the Study:

• To analyze immune escape of BA.2 and BA.5 relative to BA.1.
• To characterize neutralization profiles against BA.2 and BA.5.
• To map the antigenic space of SARS-CoV-2 variants.

Main Methods:

• Analysis of neutralization profiles in plasma samples.
• Characterization of antibody responses based on infection/vaccination history.
• Construction of an antigenic map including all Variants of Concern and Omicron sub-variants.

Main Results:

• Unvaccinated individuals exposed to BA.2 showed limited cross-neutralization to pre-Omicron variants and BA.1.
• Omicron sub-variants (BA.1, BA.2, BA.5) are antigenically distinct from pre-Omicron variants.
• BA.1, BA.2, and BA.5 are antigenically distinct from each other.

Conclusions:

• Cross-neutralizing antibodies require multiple exposures to antigenically similar or distant variants.
• Understanding the antigenic space is vital for future vaccine strain adaptations.
• The study provides insights into the evolving landscape of SARS-CoV-2 variants.