Covid-19 virus particles
Reinfection is set to rise. (Image: NIAID, CC BY 2.0, additional design by Tina Tiller)

SocietyJuly 7, 2022

Officially, just 1% have caught Covid twice. Why that’s an undercount – and set to surge

Editor-at-large
Covid-19 virus particles
Reinfection is set to rise. (Image: NIAID, CC BY 2.0, additional design by Tina Tiller)

The way cases are counted in New Zealand is changing, and so is hospitalisation reporting – a total of 15,000 Covid hospitalisations across the pandemic becomes 8,490 hospitalised ‘from’ Covid.

New data shows a tiny proportion of Covid cases officially recorded in New Zealand have been classed as reinfections, though that number is thought to underestimate how many have caught the virus multiple times and is set to climb substantially as New Zealand enters its winter wave. It comes as the Ministry of Health recalibrates the way it reports reinfections, as well as changing the way hospitalisations are accounted for, to distinguish between those hospitalised with Covid as an underlying or contributing factor and those who have tested positive but are in hospital for reasons other than Covid.

The reinfection peril

About 1% of the Covid cases reported in New Zealand over the course of the pandemic have been recorded as reinfections, while fewer than 200 people have registered a triple infection. That number is very low compared to other parts of the world, reflecting the country’s closed borders for much of the crisis. The winter wave, which is increasingly powered by new subvariants better equipped to defy the immunity from previous infections, means those numbers will surge, while public health systems and messaging must accordingly race to “catch up”, an expert has warned.

Data from the Ministry of Health provided to The Spinoff shows that of the total 1,403,073 Covid-19 cases reported as of today, about 1%, or 14,010, are reinfections. Of those, 9,573 were detected between 29 and 90 days after a previous positive test. 

In today’s update, 351 of 11,084 newly reported cases (just over 3%) were reinfections. Of those, 112 were reinfections confirmed between 29 and 90 days since the previous positive test.

There are 183 people who have caught Covid three times or more, having recorded positive tests separated by between 29 days and 90 days. That amounts to about one in every 10,000. “This figure needed to be treated with caution,” a ministry spokesperson told The Spinoff, “as the small number involved means any over or under-reporting could have a significant impact on the reinfection rate.”

Dr Amanda Kvalsvig, an epidemiologist at the University of Otago in Wellington, stressed that the risks of reinfection were relatively new to New Zealand – and rapidly growing. “Until this year Covid-19 reinfections haven’t been a concern in New Zealand,” she told The Spinoff. “That’s partly because pre-omicron variants tended to generate good protection against subsequent infection, but also very simply because infection rates in NZ were so low that the chances of being exposed and re-exposed were far lower than elsewhere.”

Now, she said, “all of that has changed”, meaning “our surveillance systems and public health messaging will need to catch up”. 

Even the true number, said Kvalsvig, would be significantly higher. “Almost certainly, known reinfections are a substantial underestimate of the true number. We know this because testing policy is a gateway factor in counting cases and until recently, New Zealanders were being advised not to test for 90 days after an initial infection and were being told that infection would deliver lasting protection.” 

‘Our public health messaging will need to catch up‘: Dr Amanda Kvalsvig from the University of Otago in Wellington

It underscored the importance of a prevalence study. “Until we have a population survey up and running we won’t have a handle on the true reinfection risk,” she said.

Why was such a study important? “The key here is that absence of evidence isn’t evidence of absence. We have more than enough data from overseas to know that reinfections with later omicron variants are common. That knowledge should shape New Zealanders’ behaviour through winter 2022 in terms of staying home when unwell, testing when symptomatic or before going into a large gathering, wearing a mask in crowded indoor places, and optimising indoor air quality. It’s sensible not to keep rolling the dice on this potentially serious infection.”

Last week the government cut by two-thirds the period after which someone who is infected with Covid is exempt from testing if symptomatic, from 90 to 29 days. That change has now been reflected in reporting by the Ministry of Health, which announced today the addition of 6,931 “additional previous cases arising from positive Covid-19 test results reported between 29 and 90 days after a previous positive Covid-19 test”. 

‘If you regularly enjoy The Spinoff, and want it to continue, become a member today.’
Toby Manhire
— Editor-at-large

The force of the winter Covid wave, which has seen case numbers and hospitalisations leap to levels not seen for months and predictions that we could soon return to the peaks of March, is driven by a mix of seasonal impacts, waning immunity from both vaccination and infections, and new subvariants that have proved much more adept at dodging human defences.

“As immunity from the vaccine and a previous Covid-19 infection wanes reinfections become more likely,” said a ministry spokesperson. “Reinfection is more common with new variants and subvariants that are better at evading the immune system. Prior immunity may be less effective at providing full protection against infection with new variants and subvariants.”

The best protection remains ensuring vaccination is up to date, as well as wearing a mask indoors and avoiding crowded or poorly ventilated environments. 

“For most people illness caused by reinfection is likely to be no more severe than a first infection, but they can experience different symptoms,” said the spokesperson. “Evidence on reinfections is evolving rapidly. We are constantly monitoring what’s happening internationally and updating our guidance to ensure it is in line with the latest public health advice.”

New reporting on hospitalisations: ‘from’ vs ‘with’

As well as changing its reporting approach to include more information about reinfections, the Ministry of Health has revised the way it details hospitalisations to show “where Covid-19 is an underlying or contributing factor, and clearly distinguishing this from when a person with Covid-19 may have been hospitalised for non-Covid-19 reasons”.

This reveals that since the start of the pandemic 8,490 people have been hospitalised from Covid-19, including 305 that have required intensive care. The previous total, tallying all people with Covid-19 who had been hospitalised, was just shy of 15,000. 

Explaining the change in methodology, a ministry release stated: “Our response to both the current and any future outbreaks depends on a strong understanding of the burden on Covid-19 on our communities, especially when infection leads to severe illness. Over recent weeks, the Ministry has been working on expanding what we know about hospitalisation.”

The ministry also provided the following details: 

  • 1,878 – just over one in five – of those hospitalised from Covid-19 spent less than 24 hours in hospital.
  • The median hospital stay from Covid-19 is three days.
  • Among people over the age of 20, the Covid hospitalisation rate for those who are unvaccinated is nearly six times higher than for those who have been boosted.
    (“As our data quality improves over time, this gap between hospitalisation rates of vaccinated and unvaccinated increases.”)
  • For unvaccinated people hospitalised due to Covid-19, the rate at which ICU care is required is roughly double the rate for those who are boosted. 
Keep going!
Photo: Poutiri Trust / Supplied
Photo: Poutiri Trust / Supplied

SocietyJuly 7, 2022

The Māori health providers battling mistrust over childhood vaccines

Stuff.co.nz
Photo: Poutiri Trust / Supplied
Photo: Poutiri Trust / Supplied

Childhood vaccination levels were already worryingly low, and then Covid hit. Kirsty Johnson speaks to healthcare workers facing an uphill battle to get children immunised.

This story was first published on Stuff.

On the sidelines of a women’s rugby game at Tauranga domain, two healthcare workers huddle in blue ponchos under a white tent. It is pelting with rain, and freezing cold. But the staff from Poutiri Wellness Centre are on a mission: to prevent a looming healthcare crisis.

This time around, it’s not Covid-19, but the spectre of the childhood diseases of measles and whooping cough that’s driving kaupapa Māori health services across Aotearoa to take their clinics into communities, working wherever they can.

In the Bay of Plenty this month nurses have been on marae, in bowling alleys, even on the ferry to Matakana Island. In Tauranga South last month, a vaccination hub named Rangiora – funded by a partnership between government and iwi – opened in a mall.

“We’re not here by default. We’ve chosen to be at a location of a mall site so that we can be a part of everybody’s day to day, said Ngāti Ranginui chief executive office Mel Tata at its opening. “The Warehouse, Countdown, Rangiora.”

Even before the pandemic hit, New Zealand’s childhood immunisation rates were dire. In some areas, they’re now the lowest they’ve been in 10 years. The ministry has a childhood vaccination target of 95%, the coverage needed to ensure herd immunity. But the national immunisation rate for six-month babies is around 75%. And for Māori babies that rate is only 55%.

Take-up rates are worst in remote areas like the western Bay of Plenty, where poverty, historic mistrust of the health system among Māori, and rampant misinformation have combined to create a huge challenge for clinicians.

“For us it’s almost a perfect storm,” said Te Puke’s Poutiri Wellness Centre CEO Kirsty Maxwell-Crawford.

Poutiri Wellness Centre CEO Kirsty Maxwell-Crawford says hammering the vaccine message turns families off. (Photo: Supplied)

“In the last two years, parents have struggled to access primary care, people are swamped by Covid, they have immunisation fatigue… and in the middle of that they’re trying to put food on the table and keep the power on.”

Babies are supposed to get whooping cough jabs at six weeks, three months and five months, while the two MMR doses for measles, mumps and rubella are given at 12 months and 15 months.

But Maxwell-Crawford said when people are so busy, or don’t have secure housing, or access to a car, those targets have little meaning to people’s lives.

“We realise that when families are stretched, keeping to a vaccination schedule is not a priority.”

Vaccine hesitancy was also rife in remote communities, and had become noticeably worse since vaccine mandates were introduced amid the Covid-19 outbreak.

Each week, Maxwell-Crawford and her team visit schools, to talk to leaders about what Poutiri can offer, ranging from clinical support, to social services.

Previously, this health check-ups would have included a vaccine check for students.

“But it’s got to the point where some communities don’t even want us to ask families if they want immunisations,” she said.

“Schools impress, over and over again, that families are over it, they don’t want to hear about it, they don’t want to be told they’re overdue.”

When families expressed such views, health workers had to take note and be guided by them, Maxwell-Crawford said.

“If you’re push, push, pushing an agenda, families just stop engaging. They will walk away,” she said. “Instead we have to listen, build a relationship, and then we hope families will become more open to a conversation.”

“Yes we need MMR and whooping cough vaccinations, but the way we are going about it is putting people off,” she said. “For us, it’s about hearing and responding to families’ priorities.”

Immunisation Advisory Centre director Nikki Turner said she was deeply concerned about a potential measles epidemic, particularly with the border opening, and about whooping cough because New Zealand was “due” an outbreak.

Whooping cough, which was particularly dangerous for youngsters, with more than half of babies under one needing hospital treatment, reared its head about every 4-6 years, she said.

University of Auckland Immunisation Advisory Centre medical director Dr Nikki Turner.
University of Auckland Immunisation Advisory Centre medical director Dr Nikki Turner (Photo: Supplied)

Turner said to get immunisation rates up, building trust was extremely important, as were flexible, practical outreach services – rather than relying on the traditional model of running clinics 9-5.

“You need families engaging with the right providers,” she said. “But outreach services have always been underfunded. That needs building back up again.”

Bay of Plenty health district’s Brent Gilbert-De Rios said it had learned lessons from the Covid vaccination roll-out that it was now applying to a broader vaccination push.

Part of that was funding providers like Poutiri to do what they did best.

“We believe in supporting providers who have long-standing relationships with whānau and communities to help people overcome mistrust of immunisation,” he said.

Maxwell-Crawford said while the challenge ahead of the health practitioners was daunting, it was not insurmountable.

“We will chip away and focus on families. Some of this is unpicking six generations of growing mistrust,” she said.

“In some ways, it’s exciting. For the first time the government is allowing us to be innovative – we’ve never been able to get on a pahi and ask the community what they want, and go and deliver it to them. That is exciting for us.”

Society