As the early days of the Covid-19 pandemic raged in Ireland, a small debate was taking place on the fringes.
Much of the talk centred around closing pubs or schools or cancelling rugby Six Nations games, a debate on how best to tackle the virus on the whole began.
There were arguments about closing down the airports and trying to completely insulate ourselves from the virus as we sought to "flatten the curve".
But as the country went from lockdown to reopening to lockdown to reopening to a third lockdown, with tiers and roadmaps and watching for spikes in daily figures, the notion that we could return to normal before a full vaccination schedule is complete has lingered away in the background.
The argument is largely driven by the Independent Scientific Advocacy Group (ISAG), a group of doctors and scientists who believe that the plan is not just viable, it's imperative.
Those against write it off as a fantasy that does not reflect the realities on the island of Ireland or how we live.
While the idea has gained support as the country lurched into a third nationwide lockdown, one with no clear end in sight, politically and societally the move to get behind a "Zero Covid" strategy has been limited.
Only Solidarity/People Before Profit has openly embraced the model, though many politicians have said that it would be desirable if they believed it was achievable.
Some now say that with vaccines on the horizon, the idea has run its course and is no longer necessary, but proponents say it's needed more than ever.
Despite what the name would suggest, Zero Covid does not necessarily mean getting and staying at zero daily cases of the virus per day.
Simply put, it means "crushing the curve" of the virus to the lowest possible level and implementing a range of measures to keep it there.
- dramatically beefed-up public health departments
- expansive testing and tracing capabilities
- mandatory quarantine for everyone coming into the country
- restrictions around the border
- making quarantining or isolating easier and cheaper
- What is the argument in favour?
The major argument in favour, in the words of ISAG member and Assistant Neuroscience Professor at Trinity College Tomás Ryan, is "the silver medal".
"The runner up prize is getting to Level 1 restrictions. What we would call Zero Covid would be Level 0 on the Government's plan — that is the Aviva Stadium is open and rugby is being played in front of 60,000 people with no masks.
But the runner up prize is pubs open, gatherings of 100 people and no more lockdowns. That's a very good silver medal."
Mr Ryan says that even with vaccines on the horizon, the "horse hasn't bolted" on the idea, saying that an aggressive approach would see normal life return much sooner than currently envisaged.
"You're really looking at November for a full rollout of vaccines here. With a Zero Covid approach, we could be back to normal by June.
"However, this isn't as radical an idea as it may seem. NPHET actually suggested the move in a letter to the Government on May 8, with exceptions for essential workers.
"In August as cases began to rise again, NPHET sounded the alarm again and called for a ban on non-essential travel as nearly 8% of cases at the time were linked to travel.
"While (mandatory quarantine) remains NPHET’s preferred recommendation, if this is deemed unworkable or disproportionate, the NPHET again recommends that consideration is given to the introduction of a travel ban on non-essential travel for those countries with particularly high incidence rates.”
Mr Ryan says that this focus is the wrong one.
"In May and June travel was really low and it's still 10% of what it was. What are we protecting here? Why should the rest of us pay a heavy bill for the travel of others into the country?"
He said Ireland had already shown that county-wide lockdowns can work. With an investment in public, he argues, this could be made more local.
"Imagine there was a massive outbreak in Cork city. We would be able to put a public health barrier around it to keep cases down.
"The alternative is to wait for vaccines for most of 2021.
"We missed an opportunity in the last lockdown and the summer and the British B117 variant makes living life at Level 3 untenable, so we may have to live with the virus or drive it out."
People Before Profit TD Richard Boyd Barrett says the plan could be used to "save the summer" and says the current government plan has "failed spectacularly".
"Thus far each lockdown has been wasted. This country needs a new direction and a new plan. That plan is Zero Covid.
The biggest and most well-known success story is New Zealand. In early June, the country declared itself Covid-free and rugby fans who get up early on weekends will see their games going ahead with thousands of fans in attendance as life returned to some level of normality.
New Zealand is seen by many to be analogous to Ireland because it is an island of roughly the same population. The country went 102 days without a case before an outbreak in August. But this was quickly brought under control and cases have remained low since.
Writing in the New England Journal of Medicine, a group of investigators from the University of Otago summed up what New Zealand did well:
"Rapid, science-based risk assessment linked to early, decisive government action was critical. Implementing interventions at various levels (border-control measures, community-transmission control measures, and case-based control measures) was effective.
"Future lessons for New Zealand include the need for stronger public health agencies that can better assess and manage potential threats and for greater support for international health organisations, notably the World Health Organisation."
The authors praised the country's Prime Minister, Jacinda Ardern for creating a sense of national pride in the response, but Ms Ardern said that the decision came down to more pragmatic metrics - hospital and ICU capacity.
“I remember my chief science adviser bringing me a graph that showed me what flattening the curve would look like for New Zealand. And where our hospital and health capacity was. And the curve wasn’t sitting under that line. So we knew that flattening the curve wasn’t sufficient for us.”
Similarly, Australia has reached zero community transmission and outbreaks are being dealt with quickly as they arise. The two are held up as the gold standard for what can be achieved in dealing with the virus.
The key to getting the idea to work, proponents say, is to scale up and fund public health teams. Professor Anthony Staines of the School of Nursing at DCU says that this would mean large numbers employed for a short time.
"We could stay in this lockdown until March — but we have to make use of the time to really beef up public health teams.
"We spend hundreds of millions on the Pandemic Unemployment Payment, as we should, but we should have €1 million a week extra going on public health.
"South Korea has 2,000 contact tracing teams of four people each. That's 8,000 people. We would probably need 700 teams who can put together a picture of what is going on and react to local outbreaks.
"We would need them for about a year. Hire them now, train them now, let them loose in three weeks. I think we'd find that we could get out of lockdowns faster.
"We have two paths in front of us — one is Level 5 for a long time. Going back into lockdown in November cost a lot of money. Lockdowns cost money. But so does the circulating virus because people are afraid to spend."
The trickiest set of restrictions would be around the Northern border, with suggestions of bubbles, to allow daily commuters to go about their normal business or even a cut on non-essential cross border travel, which would likely face huge political resistance.
The simplest arguments against the plan are that people move in and out of Ireland in a way that's difficult to end. As part of the EU, there is no certainty that Ireland can single-handedly suspend freedom of movement.
New Zealand and Australia have the in-built advantages of being many thousands of miles away from other countries and have been able to unilaterally impose tough quarantine On mandatory quarantine.
Transport Minister Eamon Ryan has said he believes it would "open the door" with the North.
That the Northern border is as much a political sticking point as a transit one is the most obvious and difficult hurdle. Some in the Government accept that an All-Ireland strategy could or maybe should have been pursued. But that does not, they warn, erase the political realities.
"The border, and the DUP particularly, are the real wildcard here," says a Government source.
"We can do better in aligning strategies, but we would never get agreement on closing the border in any way."
Officially, and emphatically, the Government has always been against the policy. Sources say that in the early days of the pandemic, the previous government looked into the idea but concluded that between difficulties closing Ireland's borders to the EU, the northern border and the lack of proven vaccines or treatment made that discussion a short one.
Since then, the current Government position has not changed.
Before Christmas, Labour's Ged Nash asked Health Minister Stephen Donnelly for his views on the strategy.
Mr Donnelly said it was not on the agenda:
"The Government has always been clear that a “Zero Covid” option is not one that is available to Ireland due to a number of factors, most pertinently the border with Northern Ireland.
"Our proximity to Europe and the nature of supply chains we are part of, both as an exporter and importer of vital goods, precludes such as approach.
"The clear advice from the National Public Health Emergency Team (NPHET) has been and continues to be that our overarching objective must be to suppress the virus to the lowest level possible and to maintain it at a low level.
"This is essential for protecting public health and our core priorities of education, health and social care services and protecting the most vulnerable to the disease."
The Taoiseach, too, has said that he does not believe the strategy could work.
"I do not believe in the deputy's Zero Covid approach and it is not viable when we consider our membership of the European Union, our relationship with the United Kingdom, and the seamless interaction of people in those places," Mr Martin said.
"We also have the border between North and south and the fact we are not in charge of the jurisdiction from a public health perspective in Northern Ireland."
Within government now, there are many who say they would like nothing more than to examine such a strategy but said that without the UK, or at least Northern Ireland, adopting a very strict policy at its borders and without EU buy-in to the idea, it would be a waste of time and resources.
"Our strategy now isn't perfect, but it's realistic and doable," said one minister.