A new spinoff of the Omicron variant of the coronavirus is getting attention from scientists as it becomes the dominant cause of Covid-19 infections in some parts of the world.

Experts say there's no reason to panic over the lineage, called BA.2, which was first identified in early December and has since spread to 49 countries including the United States.

"Among all the lineages of Omicron, this is the one showing a higher increase of cases. But we have to be careful in interpreting that because higher increases from a very low number are easier to observe," said Ramon Lorenzo-Redondo, assistant professor of medicine for infectious diseases at Northwestern University Feinberg School of Medicine in Chicago.
Boosters provide the best protection against Omicron variant, CDC studies show, raising new questions about what it means to be fully vaccinated.

Boosters provide the best protection against Omicron variant, CDC studies show, raising new questions about what it means to be fully vaccinated
Like the more familiar version of Omicron, BA.2 has a large number of changes -- about 20 --concentrated in the spike protein, the part of the virus that's targeted by vaccines.
Unlike Omicron, however, it doesn't cause a certain signature on lab tests called an s-gene target failure, meaning it can look like other SARS-CoV-2 variants on a first screen. That has some calling it "the stealth variant."But Lorenzo-Redondo says that nickname has caused people to think that it can't be detected in lab tests, which isn't the case.
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https://edition.cnn.com/2022/01/27/health/omicron-sublineage-ba2/index.html