Sydney, Jan 31 The BA.2 sub variant of Omicron may not increase infection numbers as the original strain or Delta, instead quietly replace Omicron, Australian scientists have said.
According to them, while BA.2, is more transmissible than the original strain there is no evidence that its more vaccine-evasive, The Sydney Morning Herald reported.
The subvariant BA.2 is one of at least three sub-lineages of Omicron.
The virus is found in about 2 per cent of local samples and has started to gain a serious foothold in England, India and Denmark, where it has out-competed Omicron and now makes up most viruses sampled.
"That does seem to suggest there is an intrinsic transmissibility advantage," Dr Adam Wheatley, who heads a research team studying the immune response to Covid-19 at the University of Melbourne was quoted as saying.
However, the high level of similarity between Omicron and BA.2 probably means that it would not cause a huge wave of disease as did Delta and Omicron, Wheatley said.
"Instead, BA.2 is likely to slowly replace Omicron, much as a variant known as D614G quietly replaced the version of the virus that emerged from Wuhan in the middle of 2020," he explained.
"Nothing ominous has come out so far. There is no reason to panic," added Professor Seshadri Vasan, who has been tracking Covid-19's variants at the CSIRO.
Further, evidence from a small number of Omicron infections tracked by British health authorities suggests BA.2's "secondary attack rate" - the chance of an infected person passing the virus on to someone else in the household - is 13.4 per cent, compared with 10.3 per cent for Omicron, the report said.
A preliminary data released by UK Health Security Agency suggests a two-dose course of vaccine provides essentially no protection against catching either Omicron or BA.2
But a booster dose provides strong protection. Data on how effectively vaccines prevent serious illness from BA.2 is not yet in.
"The take-home message is: if you are not vaccinated, please go and get that first dose. And if you are double-vaccinated, please go and book a booster," Vasan was quoted as saying.
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