Week 26: Herd Immunity, or something more interesting?

Written 19 September 2020

Why resurrect herd immunity?

Herd immunity  has been resuscitated several times from the beginning of the Covid-19 pandemic. In the UK the Chief Medical Officer mentioned herd immunity at the main scientific meeting between scientists and politicians, and the idea was picked up by the Prime Minister. Similar things occurred in Sweden, there Anders Tagnell thought that if there was no lockdown in Sweden they would have only a limited number of extra deaths due to covid-19, as herd immunity would have occurred in Stockholm by then. More recently in the UK a paper considered that the herd immunity threshold might be as low as 43%  (University of Nottingham June 20th 2020;  and Kim and Zoll Scandinavian Journal of Infectious Disease 2011, 43(9) 683-689).  Although between 50 and 95% are usually required for the herd idea to be true, the actual figures for % of covid-19 antibodies in the population are very much lower than might be expected if there was a general natural immunity coming in to being: UK 6.2%, (Office of National Statistics);  USA highest figure is for New York 23%; Sweden 19%; Yemen 3%. Numbers of new cases suggest that substantial numbers of potentially vulnerable people exist in the community. Enough said – there must be a more interesting way of thinking about why so many people are ‘apparently’ immune.

 

What is happening in the majority of the population?

For what reason do a very large proportion of the UK population avoid going outside, unless they are handwashing, wearing a mask or buying food for the family? Examples of this would be  disinclination of teachers to resume teaching, of those working at home to return to their offices, especially if they have to use public transport. Disinclination to people to fly for their summer holiday, in anything like the numbers that flew in previous years  We might describe these people as having a learned avoidance of returning to a full range of outside activities. Old people are especially likely to display such learned avoidance. There is nothing abnormal about this: if an effective vaccine were to become available, complete normality would return very quickly. Their avoidant behaviour is quite understandable, and needs no medical theorising. This group of people have largely not been infected by the virus, and represent a large group of people capable of becoming new cases. They are by no means immune – indeed, they are the people who are at risk of becoming new cases of the virus.

 

How should we understand people who ignore advice to protect others?

Fortune magazine observed: “in a democracy human behaviour has free will, including the ability to do idiotic things that put themselves and others at high risk of infection” (Garrat & Moore, July 21st 2020). Such people tend to be, on average, younger than the first group. A psychologist might say that of their five basic attributes, three are completely normal, extraversion, agreeableness, and lucidity. However, a trait assessment based upon possible abnormalities (DSM 5, p774 Assessment of the Personality trait model). Only two characteristics may be abnormal, negative affect (formerly called ‘neuroticism’) and a quality now called ‘disinhibition’. The latter is described as ‘an orientation towards immediate gratification, leading to impulsive behaviour driven by current thoughts, feelings and external stimuli, without regard to future consequences’. So a person who attends a large party without social distancing in a closed environment may have no morbid characteristics – but may be abnormal in these two respects. But rather than dwell on the negative side, they may also be young, risk-takers, unconventional and prepared to steer their own course. And they may also be keen on meeting people that they love. No need to explain their behaviour away by invoking abnormal psychology.

 

How does these two  groups fit into our conceptualisations of our covid-19 dilemmas?

The first risk-avoidant group are people are those who have learned to stay away from places where they might be at greater risk of becoming a new covid-19 case themselves.  They can also fall victim to a new active case, but they have to go out to become a new case themselves. They are protected only by observing the rules, not by any immunity!

 

The second group of people are those who defy pleas to conform are effective producers of the second wave, by the activities of people who flout rules. They do this both directly by breaking rules, and directly infecting other people, and by causing others to become super-spreaders. New cases are also produced by the actions of super-spreaders a few months earlier. Despite the fact that defying social distancing is more likely to produce new cases when people are under cover than when they are in the open, both venues are contributing to the second wave, which is upon us now. 

 

Conclusion.

People who break rules designed by politicians and scientists to limit the spread of Covid-19 are best identified by people who are rule-takers (the majority, with any luck), and investigated by the police. They will often be found to be quite normal people psychologically, but they have thoughtlessly infected others.  No cod-psychology is necessary, as these are antisocial acts.

 

David Goldberg

19th September 2020. 

(Despite Mr Trump’s best efforts, his attempts to improve the world for us oldies by early November will not succeed)