HERD IMMUNITY VS CORONAVIRUS
A NEW THEORY FOR A NEW THREAT
Most of us go out of our way to avoid viruses, but when infection seems inevitable there must be another option. As we navigate these new norms we investigate the challenges we face today, and the solutions we need, to secure our tomorrow.
"The coronavirus is the biggest threat this country has faced for decades and this country is not alone.
All over the world we are seeing the devastating impact of this invisible killer." Boris Johnson
With so much at stake we’re no longer given the luxury of ambivalence, because in this aftertime we’re confronted with a new kind of enemy as an invisible force. So, it's up to us to respond as a united collective - with a new kind of force.
When confronted with an enemy on the ground, we created an army. When confronted with an enemy on the sea, we created a navy. When confronted with an enemy in the sky, we created an air force, so when confronted with an enemy biologically, it's logical to create its relevant counterpart.
Intentionally catching a virus seems, on the surface, counter-intuitive, dangerous and irresponsible. However under specific medical conditions it’s an idea that’s difficult to refute.
With immune systems designed to engage in such scenarios it's our proposal to recruit the fittest of the population to proactively engage with viral threats under medically supported conditions.
In this article we explore the new bio-war from a theoretical perspective, to see if we could weaponise immune systems, to not just mitigate the spread of the virus, but actually reverse it.
The UK's current strategy is mainly based around the following:
‘Two fundamental strategies are possible: (a) mitigation, which focuses on slowing but not necessarily stopping epidemic spread – reducing peak healthcare demand while protecting those most at risk of severe disease from infection, and (b) suppression, which aims to reverse epidemic growth, reducing case numbers to low levels and maintaining that situation indefinitely’’
Each policy has major challenges. We find that that optimal mitigation policies (combining home isolation of suspect cases, home quarantine of those living in the same household as suspect cases, and social distancing of the elderly and others at most risk of severe disease) might reduce peak healthcare demand by 2/3 and deaths by half. However, the resulting mitigated epidemic would still likely result in hundreds of thousands of deaths and health systems (most notably intensive care units) being overwhelmed many times over.
We assume that 30% of those that are hospitalised will require critical care (invasive mechanical ventilation or ECMO) based on early reports from COVID-19 in the UK, China and Italy (Professor Nicholas Hart, personal communication) cases.
Age - %Cases, ICU and Fatality
Table 1: Current estimates of the severity of cases. The IFR estimates from Verity et al.12 have been adjusted to account for a non-uniform attack rate giving an overall IFR of 0.9% (95% credible interval 0.4%-1.4%). Hospitalisation estimates from Verity et al.12 were also adjusted in this way and scaled to match expected rates in the oldest age-group (80+ years) in a GB/US context. These estimates will be updated as more data accrue.
When mapped out under the current strategy it looks like our health system will face major challenges within the first couple of weeks of April 2020. In response to this the government have built more hospitals which should be able to support an additional 6,000 ICU beds, so we are increasing our health systems coping mechanisms to manage, but only for a matter of weeks. According to the data, we should be able to ride out the pandemic without overwhelming our health system, but this will only happen if there’s strict compliance with the UK’s mitigation strategy so by staying home you, scientifically speaking, will be protecting the NHS and therefore saving lives.
Mitigation vs ICU Capacity
Figure 2: Mitigation strategy scenarios for GB showing critical care (ICU) bed requirements. The black line shows the unmitigated epidemic. The green line shows a mitigation strategy incorporating closure of schools and universities; orange line shows case isolation; yellow line shows case isolation and household quarantine; and the blue line shows case isolation, home quarantine and social distancing of those aged over 70. The blue shading shows the 3-month period in which these interventions are assumed to remain in place.
But here’s where the problem is. With a lack of testing we have no idea how prevalent the virus is within the population so although we can mitigate it, the data-sets used are based on quite broad assumptions and lack a few essential variables I.e. this is based purely on an R0 number which doesn’t include the asymptomatic, population density or tracking (I.e. this infected via the original group from China vs this infected via their community).
In additon to that, without the data that early testing could provide all figures and projections are blurred due to the generic figures used to create the models which dictate policies. In short, although the government is doing it’s best, it’s bracing itself for when the proverbial rubber hits the road. Under most situations figures are usually treated with a pinch of salt, but with so many lives in the balance, we can only hope for a smooth landing. Given the current state of play luck will be in charge of how effective this strategy is, which isn’t ideal by any measure.
The Current Perception
According to Prof Willem van Schaik, Professor of Microbiology and Infection, University of Birmingham - 'Herd immunity describes the phenomenon that at-risk individuals are protected from infection because they are surrounded by immune individuals. The spread of the virus is thus minimised. Currently, we talk mostly about herd immunity in the context of vaccines. If a sufficiently high number of individuals in a population are vaccinated, they will provide herd immunity to the small number of people that are not vaccinated (e.g. for medical or religious reasons).
The major downside is that this will mean that in the UK alone at least 36 million people will need to be infected and recover. It is almost impossible to predict what that will mean in terms of human costs but we are conservatively looking at 10,000s deaths, and possibly at 100,000s of death.'
Dr Bharat Pankhania, Senior Clinical Lecturer with the University of Exeter Medical School, said:
'Trying to create herd immunity through Covid-19 brings in questions of safety. You can’t control infection spread to “high risk” people. Therefore, some people who become infected will develop very severe illnesses, and some of those would die.
Prof Martin Hibberd, Professor of Emerging Infectious Disease, London School of Hygiene & Tropical Medicine, said: “The Government plan assumes that herd immunity will eventually happen, and from my reading hopes that this occurs before the winter season when the disease might be expected to become more prevalent.
“However, I do worry that making plans that assume such a large proportion of the population will become infected (and hopefully recovered and immune) may not be the very best that we can do. Another strategy might be to try to contain longer and perhaps long enough for a therapy to emerge that might allow some kind of treatment. This seems to be the strategy of countries such as Singapore. While this containment approach is clearly difficult (and may be impossible for many countries), it does seem a worthy goal; and those countries that can should aim to do.”
The concept of herd immunity as a strategy to combat COVID-19 is a strong one as it’ll help protect our most vulnerable groups while mitigating the transmission rate.
Typically, the response from the scientific has been meak, mainly because the calculations are based on a national population hence the ‘36 million people will need to be infected’ statement, which therefore shuts down the conversation.
In addition there are concerns surrounding safety i.e. the possibilty of the individuals in the risk groups getting the virus and the consequences of that and the movement of people.
The idea we’re putting forward is designed to achieve 2 key objectives:
Mitigate the transmission rate of the virus by immunising key locations.
Allow for the safe return of the individual post immunisation so they can return to a form of normality.
To achieve this the immunisation centres will be medically supported with the relevant medical staff and equipment to deal with the anticipated 13% who will have a severe reaction. This idea is also designed to work alongside the current Governmens’s mitigation strategy so the population will be in lockdown.
In regards to herd immunity:
Our intention is to strategically target cities, towns or locales based upon a data analysis of the viral transmission rate within a certain area, so instead of the 60% of x national population, it’ll be 60% of y local population.
As this is intended to work alongside the current mitigation strategy, the population would be static, so that would add a significant layer of confidence when it comes to managing expectations.
In terms of execution, the current data collected could be used to calculate how many individuals of a certain demographic in a specific loctaion(s) it would take to reduce transmission, and by when, thus saving the health system within that area.
For example, we could determine that it’ll be worthwhile immunising x amount of 20-30 yo individuals in Birmingham, to reduce the transmission rate by x time, which will reduce x amount of new transmissions and therefore secure the health system within that area. The same recommendations could be made for any city, or town, so instead of just mitigating impact they can proactively fight back through immunisation.
By working this way, we will be cutting into the viruses roadmap leaving it with nowhere to go which, in combination with mitigation regulations, means that we’ll regain a sense of control. The Lockdown will be reducing impact based on it’s actual transmission while we’ll be reducing the R number, by mitigating it’s intended transmission rate.
In addition to that, depending on how many indviduals we recruit, the impact should effect the graph 4-6 weeks after the first group, but it'll also help mitigat the the second wave which will be of great value to the current strategy. This model, if adopted, will reduce the current transmission rate for this wave and the second. In essence this will future-proof the current strategy which willl help boost confidence in Governements leadership.
As our theory requires the strategic recruitment of volunteers to undergo self-immunisation with the pure intent to reduce the transmission pathway of the virus, it could be described as the conscious evolution of herd immunity. While this has both philosophical and ethical implications it's worth noting the following:
We’re all likely to get the virus at some point, this is strategising around that knowledge.
Over 80% of individuals experience mild symptoms, but due to the fact they’re in a medically supported environment it could be lower.
The current strategy of mitigation is difficult to maintain, not only are jobs, businesses and relationships strained but our mental health is also taking a hit which wouldn’t be easy to recoup.
Psychologically the lack of human contact is damaging.
As this lockdown progresses frustration will build between communities and politicians or law enforcement which won’t levy any positive outcomes.
We also have to remember this isn't the only lockdown we'll endure. Based on the modelling, we're very likely to need another one.
By strategic immunisation:
We can give individuals a tangible sense of duty, as they’ll be working together for the greater good.
Once immune they can return to work, their loved ones, or assist in other ways.
This strategy works in alignment with the current government regulations, and provides an additional layer of defense.
We regain a sense of control.
We’ll have more tangible data to help define policy.
So by adding this to Government regulations we will be:
Protecting the most vulnerable groups.
Protecting our NHS
Reducing economic impact.
Reducing social consequences of the lockdown.
Speaking to the Times, Professor Medley said: “We will have done three weeks of this lockdown so there’s a big decision coming up on April 13.
"In broad terms are we going to continue to harm children to protect vulnerable people, or not?
“If we carry on with lockdown it buys us more time, we can get more thought put into it, but it doesn’t resolve anything — it’s a placeholder,” he continued.
Under this theoretical model, by strategically immunising x amount of a participants, via local populations, the Government will have the best exit strategy.
I do believe that this is a model worth exploring as it could possibly save thousands of lives by reducing the transmission rate of the current wave and the second.
With the clock ticking we are under alot of pressure to ensure that we work together to acheive the best posssible outcomes for our collective interests.
Published March 13th 2020
List BodyWe explore 'self-immunisation' as a way of fighting the pandemic. Given the current state of play, is there a case for it?