BA.2 variants becoming unique to NZ
WELLINGTON: New Zealand’s Omicron outbreak is now being dominated by multiple BA.2 lineages genetically linked to our country — reflecting how widely the subvariant has been able to spread and evolve here.
An ESR scientist says it is likely our variant profile will shift again when reopened borders bring yet more forms of Omicron to spread alongside our own.
Within just a few months, scientists have watched the original Omicron subtype BA.1 overwhelm the Delta variant — before levels of BA.1, too, were squashed by the fasterspreading BA.2.
ESR’s bioinformatics and genomics lead Dr Joep de Ligt said genomic analysis of Covid19 samples showed BA.2 continued to circulate ‘‘almost exclusively’’.
‘‘And it’s given rise to BA.2.10 — a local lineage that’s dominated by New Zealand cases in the international data.’’
But that was not unexpected, he said, and pointed to the fact the virus had mutated enough while spreading here to branch into genetically different virus ‘‘clades’’.
‘‘The fact that New Zealand are now seeing these things means we have what we call persistent transmission chains that allow the virus to accumulate these mutations,’’ he said.
‘‘We can now also see a BA.2.10.1 — which is the next edition down this line.’’
He stressed the genetic changes had not made the virus yet more transmissible or severe.
For now, he said cases of BA.2 unlinked to our clades were rarely detected, while the most recent case of Delta was sequenced back in March.
‘‘Global data tells us that Delta is now reported at zero percent — so it seems the Omicron variants have suppressed it to such a level
where it’s become undetectable,’’ he said.
Infections with the highprofile BA.4 and BA.5 subvariants, meanwhile, had so far been confined to border cases.
‘‘Because BA.4 and BA.5 appear to have a slight advantage over BA.2, it might be that it gets displaced, just as BA.1 was,’’ he said.
Last weekend, officials reported the first confirmed case
of BA.5 in New Zealand — a traveller from South Africa — but insisted the public health settings already in place to manage BA.2 were also appropriate to manage the other Omicron types.
‘‘The good news is that BA.4 and BA.5 also don’t seem to be more severe at this point in time — and while they might have a small advantage, it’s still not likely we’d see them suddenly drive a second big wave here.’’
Modellers expect New Zealand’s next surge — perhaps as soon as late winter — to come on the back of waned immunity from either vaccination, infection or both.
With perhaps as many as three million people infected already, its trajectory is unlikely to be as dramatic as Omicron’s first wave.
Fifteen more deaths of people with Covid19 were reported yesterday, with another 5745 new community cases also recorded.
The seven day rolling average of new cases is 7608, up from 7510 last Sunday
The Ministry of Health said there were 384 people with Covid19 in hospital, down from 398 on Saturday, with eight in ICU.
The number of people with Covid19 who have died in New Zealand is now 973.
Yesterday’s new community cases were reported in the Northland (152), Auckland (1925), Waikato (459), Bay of Plenty (157), Lakes (91), Hawke’s Bay (196), MidCentral (177), Whanganui (59), Taranaki (152), TairAwhiti (57), Wairarapa (51), Capital and Coast (414), Hutt Valley (192), Nelson Marlborough (182), Canterbury (863), South Canterbury (83), Southern (480) and West Coast (49) DHBs.
There were 7068 new community cases reported on Saturday, as well as 18 further deaths.
There have now been 1,039,575 cases of Covid19 in New Zealand. —
/RNZ