Irish Ambassador to Sierra Leone during the Ebola outbreak in West Africa, penned a book with Dr. Oliver Johnson entitled ‘Getting to Zero (A Doctor and a Diplomat on the Ebola Frontline). The title, as indicated, relates to getting to zero cases of Ebola at a single time, meaning when the last infected patient had either recovered or died and there were no more known cases in existence – and then waiting 42 days to declare the region free of Ebola and the epidemic concluded.

Ebola is different to the Coronavirus. It is very different. The main difference is not that it is far more lethal – 50% of those infected with Ebola are likely to die compared to, maybe, 1% of those with Covid-19. Even that 1% is likely very high. The main difference is that the Coronavirus can go undetected and is, which is being admitted/assumed in the UK, going undetected in thousands of cases, because carriers may be asymptomatic or have mild symptoms easily mistaken for the common cold, or the ‘flu, and recover quite quickly. However, as they are undetected, they do not know that they are carriers, and can pass on to others completely unawares. And this can happen often, easily and quickly.

With Ebola, every known carrier exhibits very extreme, graphic and horrific symptoms. Thus, every case is known. And when every case is known, the people that person may have been in contact with can be traced, isolated, monitored, and tested. It sounds easy – but it is far from that, however, contact tracing, along with increased awareness, understanding, (and appropriate fear), was imperative in bringing the Ebola outbreak under control. Other factors related to containing the infection through isolation were of course extremely important as well. The details can be found in the above-mentioned book as well as many other chronicles of the destructive outbreak.

Given the nature of the Coronavirus outlined above, it is impossible to manage the outbreak in the same way, and the idea of controlling the outbreak and manoeuvring to ‘get to zero’ is unlikely, if not impossible. Probably this is well known but is not being said explicitly as the strategy of ‘getting to zero’ is not being talked of, although the assumption is that somehow this is where the outbreak is expected to go.

As a strategy, it would be something akin to the Ebola approach, of reducing the number of cases, through containment, contact tracing, etc so that the country can revert to a normal life. As one single case of the virus can restart the current cycle we are on, it would require eliminating the possibility of new cases arriving into the country as well as managing the cases already here. And whittling that number down. As it stands, with 54 cases on the 16th of March, such a process seems plausible as the numbers remain manageable, but we are not hearing about that strategy, probably because of the silent spread of the unknown – asymptmatic – cases in the community.

The approach taken by the UK, called reckless by many, seems to have accepted that getting to zero is not a possibility and that the only approach is to develop ‘herd immunity’ through either exposure or a vaccine. In the absence of a vaccine, it seems that exposure is the only way to develop herd immunity. With the levels of fatality assumed to be 1% or less, nearly all coming from the over-70s, the strategy seems to be that exposure of most of the population under 70 will develop herd immunity, protecting all those at risk of dying- approximately 10% of the 10% over-70. So keeping the over-70s, and other at risk individuals, safe is the pragmatic approach, rather than isolating the carriers – as they cannot all be known. Reckless it has been called. And a gamble with people’s lives.

It is a very difficult call to take. Even with that decision, the ‘curve’ needs managing in order to ensure the health system can cope with those that need not die from the disease, but will need ICU care and treatment. It is not clear over what period of time the curve needs to be managed, in order to make the situation manageable. How flat does the curve need to be in the UK to avoid chaos?

In Ireland, the strategy is, at the moment, to delay, in order to flatten the curve. However, it is not clear how flat the curve needs to be to be manageable (on the Y-axis measuring number of cases), nor how long the curve needs to be (on the X-axis measuring the time the cases are spread out over). However, if it is accepted that the strategy is not to get to zero, then the significant difference between the Irish and the UK curve is going to be the shape. If the strategy is not to get to zero (in the sense used in the Ebola outbreak), then when does the pandemic in Ireland come to an end? It must be when there is herd immunity – either from exposure or from a vaccine – leading to no more cases.

If the strategy is, though unstated, to get to herd immunity through exposure, meaning at least 60% (but probably it needs to be closer to 90% to return to normal human interaction), then this means approximate 3 million people need to be exposed to the virus. If we are at 54 cases on the 16th of March, and to maintain that level, we would be dealing with this situation for 55,000 days or 152 years. If the situation was limited to a single year, it means we would be averaging more than 8,000 cases a day, over the course of a year. In the UK, this would be something like 140,000 cases a day over a year – for this to be manageable, a huge amount of those cases would need to be asymptomatic, which has been hinted by representatives of the UK govt who assume there are already 5 or 10,000 cases in the community. It just doesn’t know. The US State of Ohio assumes it has 100,000 cases in the community.

All of this makes statistical analysis or health system planning almost impossible. What it does mean is that the fatality rate is almost certainly far below 1%. Speaking to the House of Commons Health Committee, Professor Chris Whitty said: “I am reasonably confident 1% is the upper rate of mortality,” he said. “If you are missing all the mild cases, all the asymptomatic cases, you end up with an exaggerated view of what the mortality rate is.”

But it also makes it almost impossible to plan for when herd immunity will be achieved because no one knows how many have acquired the virus, in order to plan for the curve that is being flattened, in order to naturally, gradually, get to zero through herd immunity. It also brings into question how valuable a vaccine will be in six months or a year, if it is impossible to know where immunity lies. The value will surely be in vaccinating those at greatest risk.

But in the meantime, with Ireland in the delay phase for the next three weeks, we can be sure that we will not be exiting to return to normality unless there are one million cases a week running asymptomatic and undetected all over the country – with consequent fatality rates of less than 0.0001% going by current deaths – which would ask the question, why all the fuss?

Looking for herd immunity seems like an impossible idea. It doesn’t mean we will be returning to normality in three months either as we can be sure it isn’t one million cases a month.

The question is, however, when can we expect to start returning to some form of normality? How long and flat is the curve the government tell us about, going to be? How flat does it have to be for the health service to cope? Therefore, how long do we anticipate it to be? And do we have an idea of how many cases are going undetected? It looks like it will be a long road even if a massive and thoroughly unlikely 80% of the cases are undetected with minor symptoms, because that means at least 600,000 known cases- or nearly 1,500 a day (known) to get to herd immunity over the course of a year. Or 3,000 a day over 6 months. Right now, those figures seem huge compared to the current situation however they may not seem so if we reach the most recent projections of 15,000 cases by the end of March.

And in the meantime, while the UK is isolating the over-70s, what is happening in Ireland for the extremely vulnerable? Is there some other advice or consideration that is not being spoken out-loud? Are there projections that this will peter out over time, through some calculus that is not being shared? Are projections possible where asymptomatic cases continue to spread the virus undetected? Do we need testing even of everyone without symptoms in order to identify those carrying the virus, isolate them in order to break the trend?

Perhaps there are epidemiologists that understand how the trends will play out, and that delay and containment can be transformed into getting to zero before herd immunity which seems like an impossible strategy. Will that require an inevitable next stage of severe lockdown (which may only be acceptable when daily cases hit the thousands) to eliminate community spread of both symptomatic and asymptomatic cases, or do we wait out for a vaccine? I am open to the possibility I am missing something very basic in the calculus of all this – being neither an epidemiologist, an immunologist, a behavioural scientist nor a public health expert. I just do not know what it is and no one is saying much more than ‘flatten the curve’ here in Ireland.

Stanford Professor Michael Levitt offers some hope that there will be a much quicker downswing – through good policy and adapted human behaviour.

Initially, Levitt said, every coronavirus patient in China infected on average 2.2 people a day—spelling exponential growth that can only lead to disaster. “But then it started dropping, and the number of new daily infections is now close to zero.” There are several reasons for this, according to Levitt. “In exponential growth models, you assume that new people can be infected every day, because you keep meeting new people. But, if you consider your own social circle, you basically meet the same people every day. You can meet new people on public transportation, for example; but even on the bus, after some time most passengers will either be infected or immune.”

Another reason the infection rate has slowed has to do with the physical distance guidelines. “You don’t hug every person you meet on the street now, and you’ll avoid meeting face to face with someone that has a cold, like we did,” Levitt said. “The more you adhere, the more you can keep infection in check. So, under these circumstances, a carrier will only infect 1.5 people every three days and the rate will keep going down.”

A good news story right now would be a very low percentage of asymptomatic carriers – although it would mean a high fatality rate, it would mean tracing and control would be possible, and getting to zero quickly, feasible. Another good news story would be a very high percentage of asymptomatic carriers, meaning a relatively low fatality rate, and a means to get to herd immunity in a manageable period of time. The worst case, the nightmarish one, is somewhere in between, where there is an unmanageable amount of untraceable, asymptomatic carriers, but not so many that indicate a fatality rate much less than 1% yet render getting to zero through contact tracing almost impossible and indicate a very, very long period of severely restricted movement, or a very, very long time to get herd immunity with a lot of deaths along the way.  The latter via media sounds either too simple or it is too dangerous to be talked about, as the Gardaí set up a Public Order Unit in response to the situation, or in preparation for the real response. Hopefully the trends predicted by Levitt are what we will see sooner rather than later.

Lots of questions, no answers. Just a lot of speculation.

 


 

Dualta Roughneen is a humanitarian aid worker and was in Sierra Leone responding to the ebola outbreak