Debate - There are now 71 percent of New Zealanders who have had their first dose of the Pfizer vaccine, with just over half of those people now fully vaccinated.

Epidemiologist Michael Baker says during the first year of the pandemic elimination was the best option for New Zealand. Photo: RNZ / Samuel Rillstone

At the rate the country is going, we are just weeks away from a large majority of us being fully vaccinated against Covid-19, meaning the impact of the virus on health will be far less severe and its transmissibility greatly reduced.

So what happens after we reach that target?

Do we leave our borders closed and continue the lockdown strategy if cases appear in the community? Or do we open the borders and live with what happens?

Someone who takes the latter view is Amesh Adalja, who is an infectious diseases expert and senior scholar at Johns Hopkins University's Center for Health Security, based in Baltimore in the United States.

In a special extended discussion, First Up speaks to Dr Adalja and Professor Michael Baker, an epidemiologist at the University of Otago's Department of Public Health. Dr Baker has been at the centre of New Zealand's response to the pandemic and believes so far lockdowns have served their purpose.

But let's begin with Dr Adalja's assertion that lockdowns are unnecessary.

Because if we don't lock down, doesn't that mean asking New Zealanders to become comfortable with the thought that the vulnerable in the population will die?

Dr Amesh Adalja:

"We don't want anybody to die from Covid. Covid is a vaccine preventable illness, now is a vaccine preventable death, but I think there are many tools that you can use short of a lockdown to achieve that goal and I think what we eventually want to see is decoupling of cases from hospitalisations and death. But there's going to be some level of deaths that occur, and I think it's interesting because in New Zealand you had around 26 or so deaths.

But in the last flu season you had 500 deaths and I just worry about that precedent, because what is New Zealand going to do for the next flu season? How do you kind of square what you've done for Covid for flu? When the flu deaths are 20 times higher because of those actions you've taken and I think this is going to be something that your society has to to think about and debate, and I think it's an important debate to have."

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Professor Michael Baker:

"These are really important questions. I would like to ask doctor Adalja if he believes that elimination was an optimal strategy for the first year of the pandemic when we didn't have effective vaccines available and even up until the first quarter of this year, vaccines were in very short supply?

"I think New Zealand used basically public health and social measures very effectively as an elimination strategy. I would just like to establish from him if he thinks that's an optimal approach? And then we could talk about where we're going to from here."

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Dr Adalja:

"I would say that the approach of using short-term lockdowns would have been justified and was justified in the early days of the pandemic when not much was known.

"We didn't have much scientific evidence about what types of transmission were more or less likely, and when there wasn't access to to rapid testing or knowledge about presymptomatic transmission and the utility of masks.

"I think after that period, which ended probably before the year was up from the pandemic that that there were better ways to do this using rapid tests, using masking, using harm reduction techniques and avoiding some of the more draconian types of lockdowns.

"You have to think of lockdowns as a last resort when nothing else works, and as a policy failure.

"What I want to argue against is thinking that lockdowns are the treatment of choice for this. In in the early days, I think there is some justification for using those types of measures, but once you've got testing, once you learn about the disease, once you know about masks and outdoor vs. indoor transmission, I think that there's better ways to do this where you allow people to live, but you give them the tools to make appropriate risk calculations so they're not causing cases to spiral out of control.

"At the same time you have to make sure that hospital capacity is something that you've always got an eye on and you're trying to expand it to make sure that if you do run into trouble, you've got the personal protective equipment, the ventilators, the ICU beds and the staffing."

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Dr Michael Baker:

"We published a typology of approaches in the British Medical Journal last year and the options were, when we didn't have vaccines, elimination as an exclusion, suppression and mitigation.

"Now in the Asia Pacific region, including places like Taiwan, New Zealand and Australia we adopted elimination approaches and they have performed exceptionally well.

"And if you look at where New Zealand is at now, according to I think pretty sound epidemiological and economic metrics, it outperformed the other strategies that I think he's talking about. We had the lowest Covid-19 mortality in the OECD. Four hundred times less than the US or in the UK. We had very high levels of freedom. Minimal lockdowns in fact, and that's using the Oxford Stringency Index and The Economist normalcy index.

"We also had very good economic performance ... we outperformed most other countries in the OECD.

"So I would say by all of those quantitative indicators elimination was the optimal approach. It wasn't possible everywhere, but it did protect over 20 percent of the world population.

"So I think when you're confronted by a new emerging infectious disease, this approach has performed extremely well compared with mitigation and suppression as used in Europe, UK and North America."

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Dr Adalja:

"What I think is being constructed is a false alternative. I'm not here to defend the United States' approach. I think it was abysmal. We had a tremendous loss of life and we did barely anything correct, so this is not a contest between who did it better.

"I think there are basically two false alternatives being placed here. This elimination approach and what the United States, United Kingdom and Europe did.

"I think there are better ways to do this and in the United States we basically had evasion from the highest levels of government, an administration in Washington DC that allowed cases to spiral out of control, that prevented us from testing, didn't get us personal protective equipment and that made it impossible to actually do what actions were necessary. To test, trace, and isolate because we waited for three-and-a-half months.

"So I think that certainly the United States can claim no victory when it comes to Covid and because it was considered the most prepared country it deserves the most criticism. But the alternative isn't to just to to use these types of lockdowns. What I think we need to think about is precision guided public health.

"Yes, there are certain activities that you want to curtail when you don't have vaccines but there are many other activities that can be permitted that can be done safely. If they're done outdoors, If you rapid test people, if you, if you teach people how to risk calculate. That's what I'm arguing for."

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Prof Baker:

"I definitely want to get onto the discussion of where to from here, which is the most important thing.

"But I would just like to establish that New Zealand used lockdowns in a very selective way, and that was to stamp out the virus because we knew how infectious it was and we avoided exponential spread and we saved probably around 10,000 lives.

"These were people who would have died if we had the kind of transmission that was seen across much of the Western world.

"I would just like to establish with Dr Adelja that that actually was really an optimal response in those circumstances, and then I'd like to move on to discussing, I think, his very good points about vaccination and rapid antigen testing and so on.

"But could we just actually get some clarity around that? Because we actually use lockdowns very selectively and we use it as an early response, a vigourous response, and I think that's actually a contribution to global thinking about how to respond to a new emerging respiratory pathogen that's spreading in a pandemic way. And early on, you don't have vaccines, you just have public health and social measures.

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Dr Adalja:

"When you look at New Zealand's lockdowns, the tiers of lockdowns, I think that level 1 and level 2. Those are very reasonable and very targeted towards allowing kind of balancing the risks of Covid-19 spread with the populations need to live to be productive and to go about their lives.

"The level 3 and level 4 I think don't distinguish which activities spread the infection from which don't. That's the main issue that I have. That lockdowns are blunt. They are not precision guided and many activities get swept up in a lockdown that are not demonstrably contributing to spread, and there are ways to do things short of a lockdown.

"We have had rapid antigen testing for some time, there's been an ability to use testing to help guide actions for a long time and we know the effectiveness of masks. We know the effectiveness of moving things outdoors and increasing ventilation.

"I think that what we want to do is targeted strikes on what's transmitting and leave those other activities that are not transmitting alone.

And we have data, we know that outdoor transmission is not a major issue. It does not really occur and we know that we can do things outdoors very safely. Why isn't that incorporated into some of the thinking there?"

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Prof Baker:

"I absolutely agree with you on everything you're saying, but I just want to know from you in the first year of the pandemic, we didn't have vaccines available, rapid antigen testing became available later in the year, we just worked with the tools that every other Western country had which is these basic public health measures.

"New Zealand used them I think very skilfully and achieved very good results. I don't believe in lockdowns at all if we can avoid them, but in this instance a very rapid intense, lockdown, worked extremely well for New Zealand, and a number of other countries.

"I would just like you to say whether you think that was a good response in the first year when you didn't have these other tools available?"

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Dr Adalja:

"It was a good response for the first couple of months until we understood that mask stopped presymptomatic transmission. Masks protect the wearers and that we learned that outdoor transmission was not an issue then.

"I think you if you're going to use that type of an approach, you have to modify it based on the science and say yes, we don't want indoor gatherings, but outdoor gatherings are OK.

"We don't want indoor dining, but outdoor dining is OK.

"That's what I've been arguing for from the beginning.

"Even in the United States, a more nuanced, precision, guided, evidence based way to give people recommendations on how to do this, and I think that's what's missing when you kind of use a blanket or blunt tool."

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Prof Baker:

"We are, I think, expanding our knowledge of indoor transmission as the key setting, I totally agree that understanding where the viruses transmitted, how it's transmitted as really critical.

"We need to do much more in ventilation, in mask use. Another area, I think rapid antigen testing again is critical, so we I think we agree on all those strategies. I just find the fact that you seem to have no acceptance at all that [in] New Zealand and other countries that elimination protected and saved millions of lives.

"This strategy. And it was using the best combination of methods available then, but now of course we have other tools and we are rolling them out. Just like many other countries around the globe."

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Nathan Rarere:

So from what you've seen overseas professor Baker, do you have a like an idea in your head of "we need to have at least this number vaccinated?"

Prof Baker:

"The evidence is as high as possible. Because we know that particularly with the Delta variant, the reproduction number is so high, it's so infectious, that there isn't a herd immunity threshold that will stop circulation over this virus so.

"You have to have a high coverage and all the things that Dr Adelja was just talking about - mask use, shifting events outside where possible and very good ventilation and I think widespread use of rapid antigen testing.

"I've talked a lot with colleagues overseas and this is an area that New Zealand is behind in and I think in some countries people will routinely manage their risk with an antigen testing before they go to work. Even before they meet people. So this is a testing that New Zealanders are not familiar with at the moment but it needs to be widely used."

Nathan Rarere:

How long do we wait to stamp out this latest outbreak? What happens if we get back to level 1 and through this year and we've got 85 percent vaccinated, but there's another outbreak on Christmas Eve? Would levels of vaccination be enough then?

Prof Baker:

"Yes, I know this is the frustrating aspect of where we're at now and I think the government plan is a good one and we're transitioning from our previous model to now a model which is in this phase, it's achieving higher vaccine coverage and then reconnecting more with the outside world, which means allowing a lot more people across the border and their various pilots with that.

"Everyone in the world is learning to live with this virus, it's just about on what terms, and I think it would be very brave to predict exactly what this virus is going to do in the future.

"A lot of work is being done by scientists, particularly in the UK, and they've mapped out some of the scenarios for how new variants may emerge. They may be more infectious potentially more virulent and more vaccine resistant and the virus has the potential to change very rapidly with reassortment of its genetic structure.

"So I think there is a concern that we may get more dangerous variants emerging and actually New Zealand is in a very good position to keep its options open.

"Certainly until we have high vaccine coverage and then to think about how we're going to engage with this virus in the future. There are advantages in delaying this process as long as we can, because that means we'll have more knowledge about how the virus is evolving.

"We're getting more tools all the time, and I'm hoping that New Zealand can pivot to a strategy early next year, which really gives us the best possible outcomes."

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Dr Adalja:

"I do think that Delta is the most fit version of the virus that we've seen. It is about twice as contagious as the alpha variant and there's little room for error when you're dealing with Delta. That's what happened in the United States because we didn't have enough people with high risk conditions vaccinated in the southern part of our country. And then we saw hospitals get into trouble again.

"So I do think when the Delta variant is around in your country, you have to be very aggressive with getting vaccine into people's arms, because we know that it's more contagious, but we know that our vaccines are able to prevent serious disease, hospitalisation and death.

"So it raises the stakes when a country has the Delta variant, they have to vaccinate faster and get to those high-risk populations faster before it spreads because it will.

"In the United States, I think that we're going to likely see under 12's have access to the vaccine, probably in October.

"We know that Pfizer is going to submit for an emergency use authorisation to the FDA, so likely, hopefully by Halloween.

"That that emergency use authorisation has been put in place."

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Prof Baker:

"You cannot eliminate this virus by vaccination alone and that's why you need vaccination plus public health and social measures and all of the things that we're seeing in countries that do have circulating virus but [are] keeping the risk of disease very low [and] are using all the tools they possibly can and that, I think is is very good advice.

"One of the things that will affect the risk assessment for vaccinating children is how harmful is this infection for children?

"And I think there's some quite alarming evidence coming out about the long-term effects. And of course, because it's only been with us for about 18 months, we just don't know what these effects will be like, but there's pretty good estimates now that perhaps 2 to 3 percent of people will suffer.

"From severe long-term harm, a kind of chronic fatigue syndrome and that would would actually change the risk assessment equation hugely."