Omicron BA.2 Variant May Be Extra Transmissible

The Omicron sublineage BA.2 is making headlines for its potentially increased transmissibility as its prevalence rises in some countries, but experts aren't too concerned about the variant just yet.

Other countries, including Denmark, Norway, Sweden, and India, have seen similar growth for BA.2, Jetelina reported in her Substack email. Still, she said, it's "likely nothing like the huge transmissibility jump we saw from Delta to Omicron," which was a 500% growth advantage.

So far some 8,000 cases of BA.2 have been detected in 40 countries, according to news reports.

BA.2 is not a new sublineage. It was first detected in December and made headlines then as the "stealth" Omicron variant because it did not have the same s-gene target failure on PCR testing that BA.1 did. That's because it lacks the spike deletions 69-70 in BA.1, so s-gene targets still turn up positive.

That means BA.2 doesn't have a special signal that tells labs it's Omicron, so labs now must go to genetic sequencing to identify variants, Jetelina said.

She added that while it has many of the same mutations as BA.1, it has a lot of differences too. While BA.1 had about 60 mutations, BA.2 has about 85 mutations.