How to understand the “Stealth” Omicron subvariant and prepare for its challenge

ABSTRACT

BA.2, nicknamed “stealth omicron”, is one of three known subvariants of Omicron. BA.2 differs from BA.1 (the original Omicron variant) in some mutations, including in the spike protein. This mutation makes it more difficult to identify as Omicron subvariant on several tests, and BA.2 is more infectious and more likely to infect vaccinated people compared to BA.1. BA.2 has been detected in at least 40 countries and in all continents except Antarctica, and the World Health Organization is continuing to monitor its spread, while BA.2 is beginning to replace the original Omicron strain in many countries. This commentary provides an overview of current knowledge and unknowns about this new variant and summarizes the important study findings for the purpose of informing experts.