Omicron's distant cousin BA.2 has been on the rise in New Zealand these past few weeks, racing BA.1 for the top spot of NZ's most dominant strain. But a new study suggests it could be more severe than its counterpart.
BA.2, sometimes referred to as 'stealth Omicron', was first identified in late December 2021 and is a subvariant of the current Omicron strain BA.1.
While both are currently defined as the Omicron variant, new research emerging from Japan has suggested that BA.2 could be more severe and transmissible than the Omicron we know well in New Zealand.
The findings posted say the BA.2 variant has features that make it capable of causing serious illness, similarly to Delta.
"It might be, from a human's perspective, a worse virus than BA.1 and might be able to transmit better and cause worse disease," Daniel Rhoads, section head of microbiology at the Cleveland Clinic in Ohio Daniel Rhoads told CNN.
The study found the strain is resistant to some treatments, including the monoclonal antibody used against Omicron.
CNN reported a booster shot restores protection to the Omicron variants, making illness after infection 74 percent less likely. Antibodies from people who recently had Omicron seemed to have some protection against the strain too.
BA.2 can also copy itself in cells quicker than BA.1, which allows the virus to create larger clumps of cells called syncytia. The news outlet reported Delta also did this which was thought to be one of the reasons it was so destructive to the lungs.
However, world data is showing mixed results on the subvariant's severity.
The World Health Organisation said BA.2 is estimated to be around 30 percent more contagious than Omicron BA.1.
In some countries where BA.2 is the dominant strain hospitalisations are declining. But WHO says in Denmark - where BA.2 is dominant - hospitalisations and deaths are rising, with weekly cases in the hundreds of thousands and weekly deaths in the hundreds.
However, it may be too early to tell what the real severity of the strain is.
"Figuring out whether there's a difference in severity is very hard, but there's nothing upfront that suggests it's going to be," University of Otago virologist Dr Jemma Geoghegan told the NZ Herald.
"It is likely BA.2 won't completely dominate and we'll see numbers of both variants start falling around the same time."
