Covid-19

Eighteen months on lockdown

Analysis: A scientific paper warns mass social distancing - closing schools and many workplaces - is needed to avert millions of deaths in countries with community transmission of Covid-19

A scientific paper lays out the stark realities of life in the era of Covid-19: If you can't contain the virus, then you have to shut down society or risk millions of deaths.

The paper, from the Imperial College London's Covid-19 Response Team, led by Professor Neil Ferguson, was born out of frustration with the United Kingdom's short-lived "herd immunity" policy.

The herd immunity plan, which was abandoned after the paper was distributed to top UK officials, was to allow the virus to sweep through the United Kingdom while isolating vulnerable people, with the hope that people who caught it and recovered would develop immunity from future waves. With sufficient numbers of immune people, the theory went, the virus would be unable to reach vulnerable people in the future.

Business-as-usual leads to mass death

Ferguson and his co-authors concluded a strategy of no mitigation would lead to 510,000 deaths in the UK and, if undertaken in the United States, 2.2 million deaths there. This doesn't account for deaths from those who don't have Covid-19 but are unable to access hospital resources because the health system is overwhelmed by patients with the virus.

Critical care beds and accompanying ventilators, which are crucial to treating serious cases of Covid-19, are the issue at stake. No country has enough of them to deal with a pandemic, experts say. New Zealand is not free from this burden either - Newsroom reported on Monday that the country would reach intensive care capacity if it had 3,500 simultaneous cases of Covid-19.

Under the herd immunity or no-mitigation strategy, the number of cases in need of intensive care would dwarf the number of available beds, Ferguson writes.

"For an uncontrolled epidemic, we predict critical care bed capacity would be exceeded as early as the second week in April, with an eventual peak in ICU or critical care bed demand that is over 30 times greater than the maximum supply in both countries [UK and US]."

A draft of the paper, distributed to officials in Britain and America, was responsible for the abandonment of the herd immunity policy in the UK and increased focus on the virus from the Trump administration, the Washington Post reported.

Clearly, choosing not to react is not the right reaction. What is?

Mitigation mitigates

The authors decided to analyse the difference in outcome between a number of different policy interventions, which they grouped into "mitigation" and "suppression". Mitigation "focuses on slowing but not necessarily stopping epidemic spread – reducing peak healthcare demand while protecting those most at risk of severe disease from infection," Ferguson writes, while suppression "aims to reverse epidemic growth, reducing case numbers to low levels and maintaining that situation indefinitely".

Three mitigation options were considered, in various combinations: self-isolation of symptomatic cases; a voluntary quarantine of all households with symptomatic cases where half of households comply; and social distancing of those over 70.

Choosing to implement all three mitigation options could have a major impact, Ferguson writes, but it still wouldn't be enough to avert mass death. Under optimal mitigation, 250,000 would die in the UK and 1.1 million in the US.

"This 'optimal' mitigation scenario would still result in an 8-fold higher peak demand on critical care beds over and above the available surge capacity in both [Great Britain] and the US," Ferguson states.

Suppression more effective

Suppression offers a glimmer of hope. Deaths in both countries drop significantly - as few as 20,000 in the UK - while intensive care capacity is never surpassed. But what does suppression entail?

In short, it's mass social distancing.

It assumes self-isolation of symptomatic cases and household quarantine as outlined above, then piles on a degree of social distancing that would reduce all contact outside the home, school or workplace by 75 percent. In workplaces, contact rates would drop by a quarter as more people work from home and offices put in place protective measures to minimise physical contact. Alongside this, all schools would shut, as would 75 percent of universities.

"The second option, the suppression one, is what pretty much everywhere is now doing. At the moment, ignoring places that are trying to keep it out like New Zealand, most places can’t contain it. It’s going to wash over and they have to work out how you actually manage that to protect the public," Otago University Department of Public Health's Professor Michael Baker said.

How long would this last? Until there's a vaccine, Ferguson writes.

Major change in way of life

"The major challenge of suppression is that this type of intensive intervention package – or something equivalently effective at reducing transmission – will need to be maintained until a vaccine becomes available (potentially 18 months or more) – given that we predict that transmission will quickly rebound if interventions are relaxed."

Baker concurs with this assessment. "You have to keep doing this until you have something else you can offer people and that, in the end, is a vaccine or possibly a very good anti-viral medicine," he said.

Now, there's some flexibility here. With appropriate monitoring of hospitals and communities, you could reopen schools and ease social distancing requirements whenever - in the UK - the number of ICU beds occupied by Covid-19 patients dropped below 50. If the number of patients in ICU then rose to 100 again - as researchers say it would - those requirements would snap back into place.

In other words, that's two months on intense social distancing, one month off - for the next 12 to 24 months.

Containment an option for New Zealand

Bleak, right? Fortunately, Baker says we don't necessarily have to reach that stage.

"The remarkable thing is that Covid-19 is containable, as has been demonstrated by China and a lot of those other countries now, they basically know about this because they were a part of SARS, they know what you need to do and they’re doing it," he said.

"This is really great leadership from the Government: they’ve committed New Zealand to doing the same. It’s just a matter of delivering it. It can be done."

The paper was written for countries already experiencing widespread community transmission – with the UK and the US particularly in mind. New Zealand doesn’t yet have any community transmission, although with news today that 150 Dunedin secondary school students are in self-isolation after coming in contact with a student with Covid-19, that could soon change.

By effectively closing our borders and working to rapidly ramp up testing for the virus, New Zealand has dedicated itself to containing the virus. We already know our medical system has even less capacity per capita than those of other countries, with New Zealand ranking near the bottom of the list in ICU beds per million people.

Small-scale suppression and large-scale containment

The plan is to keep community transmission to a minimum and target areas experiencing outbreaks with robust interventions, Director-General of Health Ashley Bloomfield told reporters on Wednesday.

"We've got a paper that just came through overnight to the Prime Minister's Chief Science Advisor that looks not so much at the modelling but at what you can do to prevent that big peak. What we have to date been talking about is flattening the peak, but even if you do that, you still likely exceed your health system capacity," he said.

Bloomfield clearly referenced the staged suppression technique described in Ferguson's paper.

"Our approach - and this is what successful countries have been doing - is you want to have a series of small peaks over a longer period of time and you amplify up quite stringent controls to ensure that you don't exceed your health system capacity. Then as it goes down again, you can ease those and be prepared to ramp them up again."

"This is what looks to be the most successful strategy. What we have been able to do in New Zealand is buy ourselves time to look at what is successful and then apply the right interventions at the right time."

"We are in containment mode, which is the step before you have widespread transmission," Baker told Newsroom. "All of us are so appreciative of the Government for its initiative on this. I think the entire health sector rejoiced on the weekend when the travel restrictions were announced."

Country needs breathing room to prepare

Baker says this is all well and good, but we still aren’t testing enough people. He worries we could have community transmission and not know it yet because, until recently, New Zealand had only tested an average of 11 people per day since it first started testing on January 31.

"The stamp it out part, the testing has not been widespread enough. It’s basically a new thing for us to do this at scale and there’s been not enough testing so we could have Covid transmission," Baker said.

Jacinda Ardern rejects this characterisation of the country’s previous testing efforts, telling Parliament on Wednesday it was "an inaccurate way to display what's happening with our testing. As you would expect, when New Zealand had no cases, there weren't many tests. Over time, they have increased".

Nonetheless, Baker insists we need time to scale up our capability to be able to test on the scale that countries like South Korea are. South Korea, a country of 51 million people, has tested more than 240,000 people and has so far had success in keeping mortality rates low and flattening the epidemic curve to keep the number of cases requiring intensive care within its capacity.

For Baker, suppression in the short-term is the answer. If we moved spring school holidays forward and encouraged people to all begin working from home, that would give New Zealand the time it needs to ramp up testing capacity. In a month, those restrictions could be eased and the country would have the ability to more capably monitor and contain potential outbreaks.

"The next month is really critical and I think there is an argument for taking a full suppression approach for the next month or so, until you’ve done a lot of testing. At the end of that, you might breathe a sigh of relief and say that we haven’t got it or we nabbed all the cases," he said.

Otherwise, we’re just as good a candidate for 18 months on lockdown as any other country. Baker says that's something New Zealand might need to prepare for - psychologically as well as logistically.

"It’s one thing to hear about it and see it happening at a distance. It’s like watching a Netflix series from overseas, but actually, that will be us if we don’t contain it," he said.

"It’s a new way of living that’s pretty foreign. It’s pretty obvious that no one alive today has seen a pandemic like this."

Read more of Newsroom's Covid-19 coverage here. 

Covid-19 is transmitted like the flu. The Ministry of Health recommends that all New Zealanders wash their hands frequently and refrain from touching their face in order to protect themselves and others. Call Healthline on 0800 358 5453 if you have any symptoms and have been to any countries or territories of concern or have been in close contact with someone confirmed with Covid-19.

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