The most recent and highly transmissible Covid variant, Omicron, has become the most common form of Covid today. Nearly all Covid infections around the world are from the Omicron variant, known as BA.1.
There is a rise in cases of another strain that is closely related to Omicron, BA.2. In certain parts of Europe and Asia, it is beginning to surpass the original Omicron. What is known about this variant, that is the cousin of Omicron?
The original omicron accounted for nearly all cases last week, with 98.8 percent of sequenced cases that were submitted to a public virus tracking database known as GISAID being the Omicron variant. According to the World Health Organization, some countries are now reporting recent rises in BA.2.
BA.1 and BA.2 aren’t the only sub-variants under the Omicron family. There is also BA.1.1.529 and BA.3. All are genetically closely related, however, the differences in each lie with how mutations alter their behaviors.
A virologist tracking the evolution of Covid at Fred Hutchinson Cancer Center, Trevor Bedford, reported on Twitter over the weekend that new Omicron, BA.2, now represents approximately 82 percent of cases in Denmark, eight percent in the U.S., and nine percent in the UK.
BA.2 is known as a “stealth” sub-variant, because it does not have the same target gene missing that its predecessor BA.1 does. BA.1 is missing one of three target genes, which are the common genes used in PCR tests. Because BA.2 is not missing this target gene, scientists are monitoring the variation the same way that they did in all variations prior, including the highly transmissible Delta variant.
Early reports signal that it is possible BA.2 is even more infectious than BA.1, but there is no concrete evidence thus far that the variant is more likely to escape vaccine protection.
It is also not likely that it is any more severe than BA.1. However, health officials in Denmark said that they estimate BA.2 is 1.5 times more transmissible than BA.1.