The likely reason for 'stealth' Omicron's recent success --study

 

The ability to spread more easily from person to person appears to be the superpower that is driving an upstart sibling of the Omicron variant into wide circulation, a group of scientists has surmised.

That conclusion about the virus known as "stealth Omicron" is explained in a brief report published this week by the New England Journal of Medicine. It's based on the team's finding that the virus, whose official name is BA.2, is only slightly better than the dominant BA.1 at evading the protective effects of COVID-19 vaccines.

Both of the Omicron "subvariants" have a common core of genetic mutations. But each has a few that the other doesn't. For instance, BA.2 lacks a mutation belonging to other versions of Omicron that makes it easy to differentiate them from the Delta variant. (Hence the "stealth" moniker.)

Epidemiologists can watch BA.1 and BA.2 compete against one another in a race to infect people and tell you which is winning. But scientists who study the evolution of viruses would like to understand not just which is winning, but why. As they gain more insight into how individual mutations change a virus' behavior, they can be better prepared for its next genetic shift.

Right now, BA.2 is making a solid run against BA.1 in the United Kingdom, and may be implicated in the resurgence of COVID-19 there and in other European countries.