nhs virus
Source: NHS UK

The UK’s Herd Immunity strategy, explained

Picture of Rosanna Nizam

Rosanna Nizam

Rosanna is a 2nd Year Accounting and Finance student at University of Nottingham.



There may not be many similarities between Boris Johnson and Disney’s animated character Lord Farquaad, seen in the popular franchise Shrek, but there is one. Recent comments by the British Prime Minister that “many more families are going to lose loved ones” strikes an uncomfortably similar tone to Lord Farquaad’s attempts to motivate his citizens into a perilous journey. 

“Some of you may die, but it’s a sacrifice I’m willing to make” said the character, voiced by John Lithgow.

The UK’s previous strategy of “herd immunity” is one that has come under fire not only from the World Health Organisation (WHO), but from leading scientists across Britain’s top universities as dangerous and risky, posing a severe threat to the lives of many Covid-19 victims as the National Health Service strains under the pressure. 

Explaining “herd immunity” 

The comparison of the process of herd immunity and vaccination-driven immunity.

 

Herd immunity occurs when more than 60% of a population has developed resistance to a contagious disease, thus making it harder for the disease to spread.  Usually, herd immunity is achieved through mass vaccinations programmes, but in the absence of it, the UK will need to rely on a risky strategy of allowing the virus to sweep throughout the population. 

The population that survives the illness will build immunity as the immune system charges the body with antibodies which will defeat the virus if it returns. This will in turn cause the virus to be eliminated on its own as it struggles to inhibit a susceptible host. Those who have no exposure to the virus will also benefit from this as they will be safe since the virus is unable to spread. Eventually, transmission levels will fall to zero as there are insufficient people spreading it, causing the “herd” to be immune. 

The government’s rationale 

The UK’s strategy is strongly influenced by the field of behavioral economics, with David Halpern, CEO of the UK’s famous Nudge Unit, playing a big role in advising the government’s response. 

Nudge thinking led the government to place an emphasis on “behavioral fatigue”, the concern that if restrictions come into effect too early, it might induce people to become less cooperative when the outbreak swings into higher gear. Sir Patrick Vallance, the UK’s chief scientific adviser, views a herd immunity approach to be more sustainable in the long run. Although suppressing the virus with draconian measures might be temporarily successful in the coming months, once lifted, the virus would return, said Sir Patrick.

Because of its hefty economic price tag, containment measures are unsustainable in the long run. By allowing the country to chug on normally, the government ensures that factories are producing and consumers are consuming, crucial ingredients to cushion the economic fallout of the virus.

The concerns of herd immunity

However, we have to face the harsh reality that vulnerable groups exist who have a significantly higher risk of death due to the virus. Based on evidence from the two countries who were devastatingly hit the hardest by the pandemic – Italy and China – a majority of those who died from the disease are either elderly, had underlying health conditions, or both. If this high risk group is unable to survive the disease, they will sadly only contribute to the rapidly increasing mortality figures.

Source: Forbes

 

To achieve herd immunity, Sir Patrick outlined that 60% of the UK’s 66 million population would have to contract the virus to achieve herd immunity, though it could need as much as 70% or more. 

To give a further idea on the severe risks and costs associated with Boris Johnson’s approach in controlling the pandemic, we find that:

  • 60% of the UK’s population would equate to 39.6 million people
  • 14% of cases in China, to date are severe and involve hospitalisation which translates to 5.5 million people in the UK. 
  • 5% of cases in those countries are classed as “critical cases” equating to 2 million people in the UK requiring critical care. 

It is questionable as to whether or not the NHS is able to bolster this figure as it is currently at risk of facing shortages in staff and supplies, which will cause the mortality rate to climb higher when the NHS is overwhelmed. Optimistically assuming a low mortality rate of 0.7% (global mortality rate for COVID-19 is 3.4% according to WHO Director-General), the UK would still have to suffer a morbid figure of 277,000 deaths. 

That being said, any death rate figures may be misleading as it may omit several important factors. For example, the figures may only pick up a small subset of those infected, usually the more severe cases, hence exaggerating the death rate. This view is reasonable, and countries that have conducted more widespread testing have reported lower death rates. South Korea, for example, tested thousands of people a day and reported a fatality rate of 0.5%. 

An even more concerning possibility which was pointed out by the chief medical officer was that “worst-case scenario planning” projected that 80% of the country would contract the virus. Assuming a 1% mortality rate, this results in 500,000 deaths. 

Has it been tried and tested?

To assess the feasibility of the proposed strategy, we can consider the Zika virus which caused an epidemic panic from 2014-15 and was declared a “Public Health Emergency of International Concern” by the WHO in 2016. In short, the virus is borne by mosquitoes and mainly caused physical birth defects as well as neurological complications. 

Source: World Health Organisation


A case study based in Brazil (in Salvador, Northeastern Brazil) where the virus was reportedly most prevalent found that 63% of the total 2.7 million population in the city had already contracted the disease, and the researchers concluded that herd immunity had halted the outbreak. 

The new strategy

After scalding criticism from the public, Boris Johnson and his chief scientific advisor backpedalled, and U-turned from their planned herd immunity strategy. 

On the 16th of March (Monday), the Prime Minister unveiled a containment strategy consisting of stringent restrictions such as a ban on mass gatherings, urging people to avoid “non-essential contact” and to refrain from going to crowded spaces and venues, in line with what many other countries worldwide are doing to suppress the virus. 

The acceleration of containment measures were also put into place, such as the testing of suspected coronavirus cases of up to 25,000 a day. This is a positive improvement as previously, testing was only carried out on those admitted to the hospital.

In light of the bleak situation that this pandemic has brought upon us, remember to take care of yourself, your friends and family and also to help those who are in need.