So-Called “Stealth” Omicron Offshoot Identified By Scientists In Three Countries

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Scientists have identified a new Covid-19 lineage responsible for a number of recent Covid cases in South Africa, Australia and Canada that displays “many of the defining mutations of B.1.1.529 (Omicron) [but does] not have the full set. These cases also have “a number of their own unique mutations,” according to analysis posted on information sharing platform GitHub. The platform is widely used by top researchers to share data and information related to Covid-19.

As a result of those similarities and differences with the original Omicron, which was first identified about two weeks ago, the new sequence is being called BA.2, while the original variant has been dubbed BA.1.

The new lineage is being called “stealth” Omicron by some scientists and news outlets because, while PCR tests do identify it as Covid, the mutations on BA.2 defy a shortcut used by scientists to identify a Covid case specifically as Omicron.

Why does that matter? It makes tracking the spread of Omicron more difficult at a time when surveillance of the new variant is critical to understanding it. Only seven cases of BA.2 have been identified thus far, reported the Guardian, the picture is still far from complete.

Per the Guardian: “To have two variants, BA.1 and BA.2, arise in quick succession with shared mutations is ‘worrying’ according to one researcher, and suggests public health surveillance ‘is missing a big piece of the puzzle.’ ”

It is also unclear exactly how or if the unique mutations in BA.2 will impact its transmissibility and virulence.

The original Omicron (now BA.1) has been identified in 19 states, according to CDC data and over 50 countries, said CDC Director Rochelle Walensky on Tuesday.

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