Covid 19 Omicron wave: Modellers confident peak has passed

After weeks of falling case counts, modellers are confident New Zealand is over the hump of its second Omicron wave – although the number of Kiwis in hospital with Covid-19 may stay higher for weeks yet.

The Ministry of Health today reported 6152 new community cases. The rolling seven-day average, however, had fallen to 6142 from 7776 the same day last week.

In all regions, daily case rates were now trending downwards for the second week in a row – and dropping by 18 per cent to July 31.

Cases among people aged over 65 – a group that'd been hard hit in this mid-winter surge – had also dropped by about 21 per cent in the past week, Public Health Agency's Deputy Director-General Dr Andrew Old said.

"While we know that some cases will always go unreported, testing of healthcare workers and our ongoing wastewater surveillance also supports the conclusion that for now at least, we're seeing a true decline and community transmission of Covid-19."

He added it was encouraging this decline was happening despite the more transmissible Omicron subvariant BA.5 accounting for an increasing proportion of sequenced samples: now up to 76 per cent of them.

Dr Dion O'Neale, of Covid Modelling Aotearoa, estimated the virus' reproduction number – or the average number of people that are directly infected by a single infectious individual – was now sitting just below one.

"So, it looks like we're going down," he said, adding it now appeared clear the wave's peak had passed.

If that trend was down to Kiwis being temporarily more cautious over catching the virus, then it could easily reverse.

But a larger, likely factor was that the population had met the wave with higher immunity than experts first suspected.

That might have been because more people than thought were infected in our first, BA.2-fuelled wave – but also that there'd been greater "immunity transfer" from BA.2 to BA.5 than initially estimated.

Some less commonly reported NZ Covid stats. The proportion of new cases that are possible reinfections* has risen from 3% at the start of July to around 6% now.

*positive test at least 28 days after the last one

— Michael Plank (@MichaelPlankNZ) August 3, 2022

While modellers had warned of scenarios where daily case rates could reach over 20,000, this wave's highest point reached around 11,500, in mid-July.

Case numbers were now tracking at the lower end of what had been forecast for BA.5, Old said.

Covid-19 modeller Professor Michael Plank said it was possible case rates could soon shift to a baseline lower than followed the first wave.

"If the current declining trend continues for another week, we could be hitting that lower level soon – partly because it's getting harder for the virus to find new people to infect, and the number of people who haven't had it yet is shrinking."

Plank said it was particularly good to see high case rates among older Kiwis were falling, given these had been driving greater numbers of hospitalisations and deaths compared with the first wave.

While hospitalisation rates remained on the high side – the seven-day rolling average sat at 748 today – Plank was hopeful these would soon follow the decline seen in case rates.

Old pointed out hospitalisation rates leapt by more than a third in the week to July 31 – and that all regions, except for the Northern region, had seen recent jumps.

But again, those rates were lower than what had been earlier modelled in worst-case scenarios, which warned of 1200 beds being filled amid peak pressure.

"While we could still reach more than 1000 occupied beds, we're tracking closer to a peak of about 850 occupied beds across the country," Old said.

"We will continue to watch these numbers closely, as there will always remain the potential for a resurgence in Covid cases and hospitalisations."

Old urged people to keep taking protective steps such as getting boosted and vaccinating, wearing masks indoors when away from home, and taking tests and staying home when sick.