Omicron subvariant BA.2 can cause severe disease, a new study said adding, “The genomic sequence of BA.2 is vastly different from BA.1, which suggests that their virological characteristics will also be different.” This comes at a time when World Health Organisation (WHO) noted that even though the BA.2 is more transmissible than BA.1, there is no difference in severity. However, WHO had time and again suggested that Omicron may be milder than delta, but it is not mild.
The researchers said although BA.2 is considered as an Omicron variant, its genomic sequence is heavily different from BA.1. “And, this suggests that the virological characteristics of BA.2 are different from that of BA.1," the researchers from the University of Tokyo said in their study, which has been posted on the preprint repository BioRxiv, but it is yet to be peer-reviewed.
When the researchers infected hamsters with BA.2 and BA.1, the animals infected with BA.2 got sicker and had worse lung function.
"Our investigations using a hamster model showed that the pathogenicity of BA.2 is higher than that of BA.1," the authors noted.
Like BA.1, the BA.2 also appears to largely escape the immunity induced by COVID-19 vaccines. Plus, it is also resistant to the antibodies of people who had been infected with the earlier variants of SARS-CoV-2
Adding to that, the authors said, “BA.2 was almost completely resistant to some monoclonal antibody treatments used to treat COVID-19 infection.”
"Together with a higher effective reproduction number and pronounced immune resistance of BA.2, it is evident that the spread of BA.2 can be a serious issue for global health in the near future," the authors said in the study.
WHO official Maria Van Kerkhove pointed out that there are a lot of studies underway that are comparing different sublineages of Omicron -what we know about their transmissibility, severity and impacts of vaccines.
“Now among all subvariants, BA.2 is more transmissible than BA.1. However, there is no difference in terms of severity."
WHO also pointed out that all other coronavirus variants, including alpha, beta and delta, continue to decline globally as omicron crowds them out. Among the more than 400,000 COVID-19 virus sequences uploaded to the world's biggest virus database in the last week, more than 98% were omicron.
Omicron was first reported from Botswana and South Africa in November last year. Its BA.1 sub-variant has since rapidly spread across the world and has outcompeted other variants such as Delta.
However, in February this year, another subvariant of Omicron, the BA.2 lineage, has been detected in multiple countries including Denmark and the UK. Now as per reports, BA.2 has started outcompeting BA.1 since it is assumed to be more transmissible.
(With inputs from agencies)
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