There are now at least 127 known cases of the subvariant BA.2, otherwise known as the “stealth” variant, circulating in almost half of the United States that international experts suggest is more contagious as omicron, according to a recent CNBC report.
But Kristen Nordlund, a CDC spokesperson, in a Monday statement to The Washington Post, cautions, “Currently, there are insufficient data to determine whether the BA.2 lineage is more transmissible or has a fitness advantage over the BA.1 lineage[omicron].”
“Although the BA.2 lineage has recently increased in proportion in some countries, it remains a very low proportion of circulating viruses in the United States and globally.”
In Denmark where approximately 80% of Danes are fully vaccinated and 60% have received booster shots, BA.2 has displaced omicron as the predominant variant, with the health ministry reporting more than 50,000 new COVID-19 infections this Friday, likely mostly secondary to BA.2, Troels Lillebaek, the chairman of the country’s surveillance committee on COVID-19 variants, told CNBC.
Lillebaek said the BA.2 variant has five unique mutations that are on a special part of the spike protein known to be associated with higher transmissibility, which Denmark’s Statens Serum Institut notes is 1.5 times as infectious as omicron, per CNBC.
There are greater differences in mutations between BA.1 and BA.2 compared to the differences between the original “wild strain” and the alpha variant, which had the first major mutation to spread across the world, according to CNBC.
The news outlet noted that the United Kingdom Health Security Agency (UKHSA) noted that BA.2 has a “substantial” growth advantage over omicron in England.
“We now know that BA.2 has an increased growth rate, which can be seen in all regions in England,” said Dr. Susan Hopkins, chief medical advisor for the UKHSA.
The agency noted there was no data on its severity compared to omicron, but preliminary assessment revealed no difference in vaccine effectiveness against symptomatic infection between the two subvariants.
Although the World Health Organization has not classified BA.2 as a variant of concern, officials warned this past Tuesday not only new variants will arise as omicron continues to surge across the world, but also will be more transmissible than omicron.