Going with the Herd…?

In less than a year since the full onset of the pandemic (an astonishingly short period of time), scientists have been able to create not just one but multiple vaccines with high efficacy in protecting an individual against infection by the COVID SARS-2 various.

This is a remarkable achievement; rightly celebrated, and anticipated as the gateway to the return to some resemblance of economic and social normality.

However, it is also important to recognize that the path to “normality” is unlikely to be linear, as there are a number of factors that are both key and still uncertain.

Firstly, because by definition, there is no available history, it remains unclear how long any of the vaccines will provide immunity

Secondly, the pace and scope of vaccination will affect how quickly a particular population (and ultimately Humanity’s 7.9 billion or so individuals) achieves herd immunity- the crucial point beyond which, while the virus may affect particular sub-groups who have not been vaccinated, or do not respond to it as expected, its transmission through the general population is curtailed. At present that is clearly not the case in most countries. To state the obvious, one has to have both a sufficient supply and the ability to administer the vaccine. The former relies upon foresight, money and manufacturing capacity; the latter upon sophisticated logistics, unbroken cold-chains of varying complexity, and mechanism to register and vaccinate individuals using some form of protocol based upon priority of need.

Thirdly, and linked to the second point, the level of the herd immunity threshold (HIT) for the virus- needs to be established, and then achieved- i.e., which percentage of the population has either been infected and survived (and so acquired at least temporary immunity against re-infection) and/or been vaccinated. This is an absolutely critical number. Unfortunately, and not surprisingly, the answer to that question remains unclear. Initial published forecasts of COVID-19’s HIT ranged from 50 to 67%, but the mutation of the virus into more easily transmissible forms means that the percentage could be as high as 80 to 90% (bordering on the same level as measles).

Fourthly, in a networked world, in which people need and wish to travel and interact across borders, the geographic pattern of vaccination will matter. In the absence of clear herd immunity being achieved in, say the US, and likely even then for reasons of public policy and perception, allowing incoming cross-border travel without continuing controls will be unfeasible- thus prolonging the negative economic impact on the global economy. Eradication, or suppression, of a pandemic virus is, therefore, a public good if it is not to become endemic and so continue to disrupt lives and economies.

It also remains to be seen whether or not the Developed World (which should soon have access to adequate supplies of multiple vaccines) will be willing either to share its surplus, or support the purchase of local supplies, for poorer countries. And this ignores the likelihood of logistical challenges to effective levels of vaccination in many Developing World countries.

At Awbury, we are not epidemiologists or biostatisticians. However, we do believe it is, and will remain, essential to understand the interaction and impact of the factors described above if we are to be able to model potential economic and political scenarios over the near and medium term. In reality, while hoping for the best in terms of the HIT of COVID-19 being reached, we must plan for delays and setbacks. To do otherwise, would be irrational. We currently take the view that 2021 is likely to be rather more volatile in macro- and micro-risk terms than many hope for, even if, on the balance of probabilities, the outlook becomes increasingly favourable.

The Awbury Team


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