Eliminate or learn to live with it - what's the Covid end-game?

graceacupuncture - 13/04/2022 - STRATEGY - 216 Views

It’s early 2022 and a nurse jubilantly jabs a needle into a compliant arm. That’s it – every eligible Kiwi who wants to be vaccinated against Covid-19 has now received two shots of the Pfizer vaccine.

The nation shudders with an almighty sigh of relief. But that’s quickly followed by a question: “Now what?”

It’s the question occupying scientists and policymakers worldwide. In New Zealand, we have a special committee dedicated to answering it, led by epidemiologist Sir David Skegg.

Around the world, countries are revealing some of the wrong answers. Israel, which has fully vaccinated 57 per cent of its population, had slashed its Covid case numbers to around 10 a day. There were grand plans to throw open the borders to vaccinated tourists. Then came the doubly infectious Delta variant. Daily case numbers this week hit a three-month high of 293 and reopening plans were hurriedly postponed.

READ MORE: * Covid-19: New data suggests herd immunity unachievable in New Zealand * Covid-19: Wellington case has identified gaps in our system, epidemiologist warns * Covid-19: The Delta variant and how 'scarily fleeting' encounters can allow the virus to spread * Covid-19: Is Australia's PM telling the truth about what vaccines are achieving in the UK? * Coronavirus: Vaccine hesitancy will fade as more information comes to light - experts

Wellington’s Delta outbreak scare also shows the super-spreading potential of a single tourist. With one carefully curated holiday weekend creating 2609 contacts, it doesn’t take much imagination to imagine a reopening scenario in which Covid leaks in and spreads merry hell.

As Otago University epidemiologist Professor Michael Baker says, New Zealand faces a fundamental fork in the road. Do you continue trying to keep Covid out, even as you ease border restrictions? Or do you accept that it’s going to become a recurring seasonal respiratory disease, and learn to live with it?

Abigail Dougherty

In 2019, Middlemore’s Kids First children’s hospital in South Auckland set up a special ward to cope with a measles outbreak. New Zealand operates an elimination model for measles.

Essentially, do you choose measles or ‘flu? Most of the world tries to eliminate measles, rapidly stamping out outbreaks from imported cases. For ‘flu, we aim to minimise case numbers and reduce their severity through free annual vaccinations for those at risk. But we accept that the virus can still circulate, killing about 500 Kiwis a year.

So you want to be free to holiday overseas and not worry about catching Covid at home, right?

The best hope of keeping Covid out of New Zealand for good is for enough Kiwis to get vaccinated to reach population immunity.

That’s the tipping point that brings the virus’s reproduction number, or R, below one. That means every infected person spreads it to fewer than one other person, so any outbreak naturally peters out. Where that tipping point lies depends on how infectious the virus is, and how effective the vaccine is.

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The Whole Truth: Will the vaccine protect us against the variants?

For Covid-19, experts initially estimated 60-70 per cent of a population would need to be protected against infection to reach population immunity. But then more problematic versions of the virus emerged.

The India (Delta) and UK (Alpha) variants are more infectious, while the South African (Beta) mutation appears less responsive to the vaccine.

The end result is the same for both scenarios – more people need to get the jab to halt the spread.

Now, modellers think at least 80-90 per cent of New Zealanders will need to be vaccinated to reach population immunity. If Delta continues its global rampage, steamrolling other variants to dominate new case numbers, that could climb to 97 per cent, according to estimates released this week.

That makes reaching population immunity somewhere between highly unlikely and impossible.

The Pfizer vaccine is currently approved only for Kiwis aged 12 and older. That means the maximum coverage – if every eligible person got the jab – would be 85 per cent.

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Immunisation Advisory Centre medical director Nikki Turner, right, gets a Covid-19 vaccine jab from Johanna Fowler (file photo).

But not everyone plans to get vaccinated. The May vaccine attitudes survey found 13 per cent of Kiwis older than 16 were unlikely to have a jab and another 7 per cent were unsure.

Only 55 per cent of caregivers said they would vaccinate their 12-15-year-olds. So the total likely vaccination coverage is about 67 per cent.

That could improve, as people see friends and family have vaccinations, or as outbreak scares reinforce the reality of rampant disease. In Britain, 84 per cent of those who initially opposed a jab changed their minds.

But, as Immunisation Advisory Centre director Dr Nikki Turner points out, there will always be low-vaccination hotspots where the virus could take hold. We saw that in 2019, when low measles vaccine coverage fired an outbreak in Auckland.

“Absolute herd immunity, where the virus could never move through the New Zealand community, is very unlikely.”

Ricky Wilson/Stuff

Air New Zealand confirmed there was a “medical event” on the last quarantine-free flight from Brisbane to Wellington.

So if keeping Covid out altogether seems a distant dream, should we just throw open the doors?

That would be unethical until everyone has had the chance to be vaccinated, Turner says. And if immunisation can’t get that reproduction number below one, a combination of vaccination, border restrictions and public health measures such as masking still might.

Border controls should be eased “in a stepwise, carefully thought-out fashion”, Turner says.

“We watch how much Covid comes into the country, and whether we can manage to stamp it out when it arrives.”

A staged reopening could start with allowing vaccinated Kiwis to leave and return without quarantine,she says. You might still need pre-departure and arrival testing, as vaccinated people have a much lower – but not zero – risk of passing on the virus.

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Professor Michael Plank, from the School of Mathematics and Statistics at the University of Canterbury.

Then you could allow in vaccinated tourists, possibly with shorter quarantine, or home isolation.

But it’s still complex. Would you treat all vaccines the same, given some are more effective than others, especially against the Delta variant? Israel plans to make tourists vaccinated with non-United States- or European Union-approved vaccines have an antibody test on arrival.

And border workers worldwide are already reporting fake vaccine passports.

Those are global questions yet to be definitively answered, Turner says. But she believes New Zealand should still manage its borders to minimise the risk of Covid outbreaks.

“At this moment we’ve got the chance to control its spread in New Zealand. We’ve done incredibly well at that. And we should keep down that track.”

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Otago University professor Michael Baker doesn’t want to give up on the elimination strategy.

Covid modeller and Canterbury University professor Michael Plank agrees New Zealand should retain its elimination strategy, at least until the end of the vaccination rollout. Then, you re-evaluate.

Even if the vaccine is eventually approved for younger children, and we can reach herd immunity, that would not be a magic bullet, Plank says. The layers of Covid defence – such as testing and contact tracing – will not suddenly disappear. But every extra vaccination reduces the risk of serious disease, and of an outbreak spreading.

“It’s not going to be sort of magically one day we think we’ve reached population immunity and we completely open the borders and go back to normal. I think we’ll see a gradual, sort of phased approach.”

Baker is damned if he’s going to give up on elimination, and he doesn’t think New Zealand should either. He may be biased, he confesses, given he was the architect of the country’s elimination strategy. He argues we should not be seduced by the likes of Britain, which has become habituated to community cases and deaths, declaring it’s time to “learn to live with the virus”.

“I find it very frustrating that at the moment we’re being bombarded with slogans from Boris Johnson and people in the northern hemisphere – countries that have failed abysmally with managing this – saying, why don’t you join us in our dysfunctional response?”

Daniel Pockett/Getty Images

Testing, contact tracing and some form of quarantine are likely to be long-term fixtures.

Baker believes New Zealand can continue to pursue elimination, at the same time as relaxing border restrictions, even without reaching population immunity. With a combination of vaccination and border controls based on risk, he’s confident New Zealand could manage any outbreaks without further lockdowns.

“If you have a highly vaccinated population, there will be less spread and fewer consequences, so you could probably manage outbreaks more like how we manage measles ones – contact tracing, quarantine and isolation, vaccination.”

Like Britain, New Zealand could split countries into red, amber and green zones by risk. The green zone would extend the Aussie and Cook Islands arrangement – a quarantine-free bubble for countries aggressively stamping out any community transmission.

Once all vulnerable Kiwis, border and healthcare workers and over-45s are mostly vaccinated, you might consider opening to amber countries, with low transmission levels, Baker says. As vaccination ramps up, that might include Britain, Europe and North America. Those travellers would have to be fully vaccinated, and have a negative pre-departure test.

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National Hauora Coalition clinical director Dr Rawiri McKree Jansen says the Government should resist any calls to reopen further until 85 per cent of eligible Māori are vaccinated.

Red zone travellers might still have to quarantine. So if I want to travel to India on holiday in mid-2022, can I?

“I’d need to know more about what is your risk,” Baker says. “If you’re fully vaccinated, what is the chance you’ll be infected and infectious when you arrive in New Zealand.

“I think some form of quarantine capacity will be with us for quite a long time. But I could see the scenario where most travellers coming into New Zealand, if they’re fully vaccinated, will avoid quarantine. That might mean they need a Covid test before they get on a flight. Maybe rapid tests at airports, which could be quite good for identifying people who may be infectious on a flight. It will be just having confidence that those precautions are good enough.”

But the gradual reopening process could take a couple of years, Baker says.

Israel’s situation shows the limits of border control effectiveness once an outbreak takes hold. Officials have declared their airport measures “futile”, with travellers making up less than 10 per cent of new cases.

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D'Angelo Martin explains why so many Māori and Pasifika people are at the head of the Covid-19 vaccine queue.

National Hauora Coalition clinical director Dr Rawiri McKree Jansen (Ngati Raukawa, Ngati Hinerangi) says having 85 per cent of eligible Māori vaccinated should be a bottom line before opening the borders.

He reckons Medsafe will approve the Pfizer vaccine for children older than 4 before the end-of-year rollout deadline, so he would consider delaying reopening to vaccinate those kids.

“The dilemma for us is, as the vaccination ramps up, if you’ve got 70 per cent of the over 50-year-olds vaccinated, they’re going to be vocal about ‘Come on, let’s open the borders, we’re holding back our economy’. But at that point, any outbreaks then are going to travel amongst the 20-50-year-olds, and these variants will still cause quite a lot of health impact.”

Jansen is optimistic those currently resisting vaccination will change their minds, once they see whānau getting protected. But what happens if we reach the end of the rollout, and still haven’t vaccinated 85 per cent of eligible Māori?

Eliminate or learn to live with it - what's the Covid end-game?

“That’s a rock and a hard place, isn’t it? We’re going to resist. There will be enormous pressure on the Government to open, and relentless resistance to opening.”

Scott Heppell/AP

British Prime Minister Boris Johnson says the country needs to learn to live with Covid.

The Government failed to prioritise vaccinating Māori, despite their risks from Covid being roughly equivalent to a Pākehā person 20 years older, so it’s the Government’s job to fund a targeted campaign to improve vaccination rates among Māori, Jansen says.

When we do reopen, he would also expect a risk-based process. If you’re from Australia,0 you’re vaccinated and there’s no current outbreak, it might be a saliva test and you're good to go.

But if you’re from the United States and you're not vaccinated and Covid is still circulating, you might need a saliva test before boarding the plane, a nasopharangeal swab on landing, and an enforced hotel or motel isolation at your own cost, Jansen says.

“I don’t think we need to go to open slather. That might be quite harmful for us.”

“We will have to live with this virus – which will continue to cause severe infections and kill people – for the rest of our lives,” England’s chief medical officer, Professor Chris Whitty, declared in mid-June.

Delta’s rampage through Britain has sent cases soaring to tens of thousands a day, and delayed the completion of the country’s four-step Covid lockdown exit plan.

But Boris Johnson remains committed to a July 19 “Freedom Day” relaxation of all internal Covid restrictions.

Australia yesterday announced it will also move from suppressing Covid-19 to living with it. Its post-vaccination pathway will progressively shift the focus from virus elimination to reducing serious illness.

CHRISTEL YARDLEY/STUFF

If level 3 or 4 lockdowns are regularly needed to stamp out virus outbreaks once the borders reopen, Kiwis and tourists might lose patience for the elimination approach.

This is option two – disease control. It’s based on the theory you can’t keep Covid out forever, so you have to accept there will be cases and deaths, but develop strategies to minimise them.

“Are we going to have to shift to disease control at some stage?” asks Turner. “That’s unanswered at this stage, really. You’ve got to keep watching the science closely. We’ve got to watch how transmissible is Covid, how effective do the vaccines continue to be, how long-lasting are the vaccines?

“If we started to lift the border controls a bit, and if we’re only getting occasional Covid into New Zealand, then you could continue to carefully lift controls. We’re in very uncharted territory here.”

If continuing down the elimination path leads to regular lockdowns, disease control could be an option, Turner says.

“If it does become too disruptive, then the alternative scenario for New Zealand is that we get as many people vaccinated as possible, so that even though Covid is in our community, it's causing less damage. That's an alternative reality that is also reasonable if we can maintain high coverage rates with a good vaccine.”

The problem with the disease control strategy is that, so far, there has been more disease and less control.

In Britain, proponents of the ‘live with it’ approach argue hospitalisation and deaths have been lower in this wave, because almost half the population is fully vaccinated and two-thirds have had at least one dose. However, you would expect a time lag between new cases and hospitalisations or deaths. Whitty warned Brits to expect a winter surge.

Baker says those advocating the “live with it” model need to be very clear about what that means. Does that mean Britain will accept hundreds of thousands of cases and tens of thousands of deaths every winter?

In New Zealand, there’s little data yet on what living with Covid might mean. Initial modelling of letting Covid run rampant produced terrifying predictions of overwhelmed hospitals and up to 60,000 deaths.

Vaccination would massively reduce those numbers, as even for the Delta variant the Pfizer jab is 88 per cent effective at preventing symptomatic disease. But just how much depends on how many people are vaccinated, the infectiousness of new variants, how effective the vaccine is against those variants, and how well it prevents people spreading the virus.

Christel Yardley/Stuff

Even with a high vaccination rate, a wholesale reopening of New Zealand’s borders could result in thousands of hospitalisations, new modelling shows.

Plank’s modelling paper, released this week, showed even if we reached 90 per cent vaccination coverage in adults over 15, the impact of letting Covid in would still be major without public health controls.

Based on a scenario of five non-vaccinated, imported cases a day over two years (the Immunisation Advisory Centre considers that unrealistically high), Plank’s team estimated the impact of a variant of similar infectiousness to the original Covid-19 strain, which had a reproductive number of about 3. That could result in 150,000 infections, 2000 hospitalisations and 230 deaths.

For a variant where every infected person spread the virus to about 4.5 people, such as the Alpha strain that originated in Britain, 1.3 million Kiwis would be infected, 17,000 would be admitted to hospital and 2200 could die.

For a variant with a reproductive number of 6 – roughly the same as Delta – infections could number 1.8m, with 25,000 hospitalisations and 3400 deaths.

Mike White/Stuff

Tourism businesses dependent on international visitors, such as Piopiotahi/Milford Sound, are struggling to survive New Zealand’s closed borders.

So then the question becomes, how many deaths is an acceptable price to pay for freedom of movement?

Baker argues we only accept 500 annual ‘flu deaths because there’s no good alternative.

“If we had vaccines like the Pfizer vaccine that could achieve 90+ per cent effectiveness and approaching 100 per cent effectiveness at stopping death, we would roll it out tomorrow and we would eliminate influenza. No-one would choose to live with influenza if they could avoid it.”

We also need to know more about the long-term impacts of Covid, with reports of neurological damage even from mild cases, Baker says.

However, an effective treatment could be a game-changer. The Hepatitis C and HIV epidemics were both beaten down by transformative treatment, rather than vaccines.

In an ideal world, Jansen can see us eventually having enough immunity to accept Covid as an annual disease like ‘flu. But not yet.

“I can see that happening – vaccine companies developing Covid/influenza combos. They might tweak their Covid one every year or two and tweak their flu one every year. I can have that fantasy that we’re going to get there within about two years.

“Once we’ve done the national round of vaccination for Covid twice, and then we just fit it into our regular vaccination programme, then we can dial down the defences.”

Alberto Pezzali/AP

While Britain's Prime Minister Boris Johnson, right, wants his country to learn to live with Covid, Australian Prime Minister Scott Morrison, left, is fighting outbreaks in a bid to continue keeping the virus out.

Even Tourism Industry Aotearoa boss Chris Roberts is not clamouring for a grand reopening to the globe.

“We are expecting a long, slow transition.”

While there’s pent-up travel fervour, border restrictions – especially if globally inconsistent – could prove barriers to tourism. Testing requirements, the possibility of getting stuck in lockdowns or being unable to return, are all possible deterrents, Roberts says.

While most Kiwi tourism businesses have downsized and adapted, areas dependent on international visitors, such as Fiordland and the West Coast, are doing it hard, he says. Finding staff for jobs usually filled by backpackers is also challenging.

And if we’re among the last to reopen, there’s a risk New Zealand gets left behind, as other countries soak up airline resources and tourists, Roberts says.

”If you slip off the radar, it’s incredibly difficult to get back on it again.”

WIKIPEDIA

Edward Jenner pioneered the whole concept of vaccination with his development of a vaccine for smallpox around 200 years ago.

Sorry folks, this one is pie in the sky, at least for now.

Baker reckons there should be capacity to vaccinate everyone on the planet by about the end of next year, making global eradication technically possible.

“That doesn’t mean it’s practically possible.”

But long term, if “functional” states routinely vaccinate, Covid could become an uncommon infection, Baker says.

Only two diseases have been officially eradicated – smallpox and cattle plague rinderpest. The world was declared smallpox-free in 1980, 21 years after the World Health Organisation started its eradication plan.

That was almost 200 years after Edward Jenner developed a vaccine to prevent the disease, pioneering the whole concept of vaccination.

But mindset rather than time makes eradication unlikely for Covid-19. If countries such as Britain and the United States choose to live with it, then it will be ever-present.

In that case, the most likely scenario for New Zealand seems to be a phased reopening that tries to keep Covid out long enough to progressively build up enough immunity through vaccination and exposure to allow it in with the least harm.

Gareth Cattermole/Getty Images

A reminder of Covid-19 restrictions in Cambridge, England.

“The end game for me will be minimal damage to the New Zealand population till we end up with a seasonal respiratory virus,” says Turner.

The only question is exactly how we get there.

Israel: With 57 per cent of its population now fully vaccinated, Israel plans to open to tourists from August (that was delayed because of the Delta case surge).

Visitors will have to be vaccinated, and undergo testing before flying to Israel, on arrival and before leaving. They must also book with travel agents, so they can be easily followed up.

Australia: Australia on Friday announced it will move from suppressing Covid-19 to living with it. The four-step pathway will progressively shift the focus from virus elimination to reducing serious illness.

Phase one is the vaccination phase. Step two will kick in at a yet-to-be-decided vaccination coverage threshold. That will mean lockdowns only in extreme circumstances, reduced restrictions for vaccinated people and greater access for students and economic visitors.

Phase three will shift to managing Covid-19 like any other infectious disease, with expected hospitalisation and death rates similar to ‘flu. Phase four will return the country to complete normality.

Britain: On July 19, Britain plans to remove all internal Covid restrictions. However, it still has border controls.

Since May, countries have been divided into "red", "amber" or "green" categories.

Low-risk green country category travellers have to complete a passenger locator form, get a pre-travel negative test and take a sequencing test on day 2 after arrival. Amber country travellers also have to quarantine at home for 10 days and take a day 8 test.

Red zone travellers, who are not British citizens or residents, are barred from entry.

Hong Kong: Hong Kong also has a border entry system based on risk. Fully vaccinated travellers from lower-risk countries can reduce their quarantine from 14 days to seven if they test negative for the virus and positive for antibodies.