New Zealand is on the verge of reporting its 3000th Covid-19 death, and an epidemiologist says the virus is still on track to claim twice as many lives as flu this year. Photo / 123rf
New Zealand is on the verge of reporting its 3000th Covid-19 death – and an epidemiologist says the virus is still on track to claim twice as many lives as flu this year.
The Ministry of Health has reported 2942 virus-related deaths since the pandemic began, as the health burden of Covid-19 continues to be felt in our communities.
“Based on the number of deaths seen so far in 2023, we can expect at least 1000 deaths this year if that rate continues,” Otago University epidemiologist Professor Michael Baker said.
“This is twice the number estimated to be caused by influenza, and three times the road toll.”
Baker said the true number of deaths caused by the virus was likely higher than what was being formally attributed to it, as it was known to cause an increase in mortality rates for at least 12 months after infection.
In any case, Baker said the virus clearly remained a leading cause of death in New Zealand: the 2448 virus-related deaths reported in 2022 accounted for about 6.3 per cent of total deaths that year.
Of 1871 cases where Covid-19 has been officially coded as the underlying cause of death, 1329 – or just over 70 per cent – occurred among those older than 80 years.
Of deaths per 1000 reported cases of Covid-19, people aged in their 90s had the highest rate, with 47, compared with just about 0.03 for people aged in their 50s.
The data also highlight Covid-19′s disproportionate danger to Māori and Pacific people – who continue to be over-represented in hospitalisation figures – along with the unvaccinated.
Those were also headline findings of a ministry analysis released last year, finding a 62 per cent reduction of risk of death among those who had received two or more doses of the vaccine.
“Vaccination and boosters still help to protect against severe disease and death, and are particularly important in older age groups and those with underlying illness,” Baker said.
“They also offer some protection against Long Covid. I’m still surprised that a sizeable proportion of the population are not taking advantage of this free service.
“I’d like more public communication about the benefits of vaccination, particularly for vulnerable groups.”
Covid-19 Modelling Aotearoa’s Professor Michael Plank noted that, while comparative data for Māori and Pacific people was complicated by the fact they had younger age structures, the equity gaps they represented continued to be a great concern.
It wasn’t a coincidence, he said, that Māori and Pacific people had higher hospitalisation and death rates and lower vaccination and booster rates.
“That’s not the only factor, there are many other contributors to that inequity that we need to tackle as well, but lifting those vaccination rates would go a long way to reducing the gap.”
While overall reported case numbers had been relatively low since the Christmas time wave, Plank said the virus continued to exact a high health burden in New Zealand.
“And that’s on top of the other respiratory viruses and infectious diseases that we already have,” he said.
“It’s common to compare it with influenza. The number of yearly deaths due to influenza perhaps averages about 500 per year, whereas Covid-19 is still significantly more than that – and it’s also on top of, not instead of [flu deaths].”
That largely owed to Covid-19′s now-widespread prevalance in our communities.
“If you look at the risk of severe disease or death per infection, it’s probably not that dissimilar, now, between flu and Covid-19.
“But it’s the fact that we’re continuing to see higher numbers of Covid-19 infections, and transmission year-round – whereas with flu, we typically get one wave during winter, and then very low levels during the summer months.”
After the large Covid-19 waves of last year, Plank said there were encouraging signs that our case trends were headed toward a more predictable “equilibrium” – provided the virus itself didn’t abruptly change.
“The number of cases, hospitalisations and deaths have been pretty stable for the last six months now; that’s an indicator that things are settling into a more predictable pattern,” he said.
“I think that, in another six to 12 months, we should have a clearer picture of what the seasonal cycle is likely to look like – and what that kind of equilibrium level is likely to be.
“So, we are moving in the right direction, in terms of the mortality rate reducing, and that’s due to a build-up of immunity in the population from vaccination and previous infections, along with anti-viral treatments in those high-risk groups.”
Baker pointed out that, compared with other nations, New Zealand’s cumulative death rate since the start of the pandemic was markedly low.
As at May 31, the rate of cumulative Covid-19 deaths per million people sat at 567 for New Zealand, compared with 797 in Australia, 3551 in the UK and 3331 in the US.
“The elimination strategy worked well in delaying arrival of Covid-19 into NZ for almost two years, giving time for development of effective vaccines and achieving high vaccine coverage before most people had been exposed to the virus,” he said.
“Even during widespread Omicron infection, New Zealand has continued important control measures, like self-isolation when people are sick, to reduce the impact of the pandemic.”
The net effect of that, he said, was that, for the course of the pandemic, New Zealand was among the few countries to still have no “excess mortality” - or the difference between how many people died throughout the period from any cause, and how many would have been expected otherwise.
“If New Zealand had experienced the cumulative excess mortality of the UK, then we would have had around 15,800 excess deaths,” Baker said.
“Or, using the experience of Sweden, we would have had 7450 excess deaths.
“New Zealand’s excess is currently around zero.”
Going forward, Baker saw a need for better measures to quantify Covid-19′s wide-reaching impacts.
One was calculating its “burden of disease” – an estimate that used a combination of years of life lost, and years lived with the chronic effects of illness.
According to one international estimate, the average Covid-19 death represented nine years of lost life.
“The second part of the calculation is adding in the long-term effects of Covid-19, usually described as Long Covid,” he said.
“This may be its biggest impact on health, but it is still poorly measured, and we won’t know its full extent for many years.”
The World Health Organisation estimates 10 to 20 per cent of people experience longer-term health effects after recovery from Covid-19.
“Even if the risk is at the bottom end of this range, it will still be important across the population.”
An Omicron variant behind a recent surge in cases in India has risen to become the leading source of coronavirus infection in New Zealand, new surveillance suggests.
ESR’s latest report shows the subvariant XBB.1.16 – nicknamed Arcturus – now makes up about one-quarter of sequenced community cases, compared with about 13 per cent around a month ago.
It also accounts for a total 27 per cent of sequences drawn from hospital cases.
Now found in more than 30 countries, the variant is behind a recent wave of cases in India, which have prompted authorities in some states to temporarily introduce masking mandates.
First identified in January – and classified by the World Health Organisation in April as a variant of interest – Arcturus is known to contain an extra mutation in its spike protein, which is thought linked to increased infectivity.
To date, however, there is no evidence to suggest it is any more lethal than any of the other 600 subvariants in the ever-growing Omicron family.
Arcturus is an XBB lineage – a group of immune-evasive hybrids originally stemming from BA.2.10.1 and BA.2.75 – which include so-called “Kraken” strain, XBB1.5, and collectively make up more than two-thirds of sequenced cases here.
Our latest #COVID19 Genomics Insights Dashboard is available, with an overview of viral genomic surveillance across NZ. Find out what's trending 🔼 and 🔽 in Aotearoa. Download the report here: https://t.co/PQBMUInsql pic.twitter.com/f3PdDY0RXq
— ESR - Science and research (@ESRNewZealand) June 2, 2023
The ESR data also revealed that an Omicron strain thought to have evolved in New Zealand accounted for about two in 10 sequenced cases.
That was FK.1.1 – a lineage derived from CH.1.1, which itself linked back to the BA.2 type that powered the country’s first major Omicron wave more than a year ago.
Last month, ESR’s pathogen genomics technical lead Dr David Winter said FK.1.1 included several mutations that changed proteins in the virus, including two in the spike protein, which it used for accessing our cells.
But those changes weren’t “obviously linked” to increased infectivity.
“We can’t be sure this lineage arose here, but widespread transmission of a virus means new mutations and changes in infectivity are always possible,” he said.
“So we’ll keep watching this lineage and for others that others that might pop up.”
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