Coming clean over hygiene

We urgently need some fresh thinking to avoid the forthcoming wave of viruses coming our way

As the pandemic and accompanying restrictions have subsided in much of the world, there are reports of other viruses now coming to the fore in new and unusual ways. Influenza, respiratory syncytial virus, adenovirus, tuberculosis and monkeypox are among a number of illnesses to have increased their incidence and shown strange behaviours in recent months. Health experts are suggesting that COVID restrictions may well have reduced our exposure and with that lowered our immunity to infectious diseases, making us all more vulnerable to new outbreaks. 

This means that a focus on effective hygiene to prevent transmission is still more important than ever.  But despite there being a huge amount of knowledge and expertise about what is needed for maintaining hygiene, there are widespread misconceptions on the topic that should now be giving us very real cause for concern.

We tend to treat hygiene as a ‘me’ issue, with each of us managing our own personal risk. But if COVID has showed us anything, it is the way that in fact hygiene as a ‘we’ issues, as my risk of falling ill is significantly influenced by the decisions of everyone else around me.

Viruses are a collective challenge, as are hygiene behaviours that can reduce their transmission. It is hardly a surprise that the provenance of our hygiene behaviours are also social and in particular reflect the way in which we share beliefs and knowledge. Much of the time this is helpful - it means we can rely on each other to understand what good looks like. But it can also be a weakness for us if what we share are, in fact, unhelpful misconceptions.

The Hygiene Hypothesis

A key misconception that we will draw on to illustrate this is the notion that good hygiene itself can be problematic, as it is to blame for reducing contact with important microbes.  A recent report sets out the way that the ‘Hygiene Hypothesis’ emerged in the late 1980s, suggesting that rising rates of allergies in children were linked to improved household amenities and higher standards of personal cleanliness. This led to the concept of ‘over-cleanliness’ that was widely publicised in the 1990s.

However, this ‘Hygiene Hypothesis’ has since been refuted as it is now understood that what is important is in fact diverse exposure to microbes that are generally harmless, and not exposure to infections from harmful microbes. While it is certainly possible that excessive home and personal cleaning practices might reduce the diversity of beneficial microbes, there is no real evidence to support this. In fact, microbiological data indicates that, after cleaning, microbes on surfaces return to pre-cleaning levels in a very short time.

Despite this development in our understanding, we still collectively cling to the notion that over-cleaning of the home is problematic for our health.  A review conducted by the International Scientific Forum on Home Hygiene found that 70% of the UK population considered home cleanliness as a factor in rising health problems, referring to the home as being ‘too clean’, ‘too hygienic’ or ‘over-sanitised’.  In another survey, they reported that 23% agreed with the statement ‘hygiene in the home is not important because children need to be exposed to harmful germs to build their immune system’.

The challenge here is that this could lead to people being left exposed, as people then stop doing hygiene practices that have an important role in preventing harmful or even life-threatening infections.

Hence there are collectively held beliefs which seem to be directly underpinning problematic behaviour and yet are difficult to dislodge.  What can we do about it?

Community of knowledge

It is well known that people will inevitably have limited understanding of complex issues such as how hygiene behaviours actually work in practice, and will therefore struggle to absorb all that much detail.  Indeed, we rely on deep social knowledge and practices that is often not explicitly taught – we simply take them on trust: ‘this is how things are done, so this is how I will do it’.  We acquire the norms, customs and conventions of those around us.

This is in no small part because we do not, and cannot hope to, have access to ‘first order representations’.  For example, as we saw with COVID, the vast majority of the population seem to accept that vaccines can prevent illness but often have little comprehension of how they actually do this.  Similarly, we often ‘believe in’ evolution but have might struggle to describe the theory or mechanisms involved. We rely heavily on our community of knowledge as a basis for our beliefs but we may not often have a clear sense of the mechanisms that underpin our beliefs and shape our behaviour.

On this basis we can see how these behaviours are not typically inspected and updated.  While much of the time this may not matter, the problem arises when the model that we have in our heads is at odds with the reality of how something actually works.  This certainly seems to be the case with the ‘hygiene hypothesis’; the model we have of exposure to bacteria or germs being helpful to our immune system has not been sufficiently updated. We struggle then to differentiate between lifestyle choices that allow exposure to a range of harmless bacteria, and the hygiene practices that protect us from harmful bacteria. 

Mental models

To address this, schema management is important:  by this we mean that when we seek out new information, we are able to fit it into existing ways we have of looking at the world. If new information does not fit in, there is a possibility it is overlooked and ignored. This means we need to share information in a way that is timely, relevant and experiential so that people are more easily able to fit conflicting information with their existing schemas. 

This translates into building on people’s understanding that exposure to microbes is a good thing (existing schema) but refining it by referencing the value of diverse exposure to harmless microbes, while emphasising that exposure to harmful microbes needs to be avoided in any circumstance.

To get these messages across in a way that resonates, we need to locate them in metaphors, images and popular stories. This is where behavioural science can lean on disciplines such as semiotics and ethnography to identify the right ‘vehicles’. These can flesh out the mechanisms that are shaping our beliefs, and can then offer much needed sense-making for people about hygiene.

Conclusions

An estimated 40,000 viruses reside in the bodies of mammals, and of these about one quarter could infect humans. Most do not, but only because they have few chances to relocate into our bodies. But with the Earth’s climate changing, then animals are forced to relocate to new habitats, searching for their preferred environmental conditions. This means that species will co-exist for the first time, allowing viruses to spill over into unfamiliar hosts, including humans.

Indeed, a recent finding suggests that even under the most optimistic climate scenarios, the coming decades will see roughly 300,000 first encounters between species that normally don’t interact, leading to about 15,000 spill-overs whereby viruses enter naïve hosts.

If we thought that the issue of hygiene had gone away with COVID then it looks as we were badly wrong. In fact our task now is to take the learnings about behaviour change from this era and apply them with greater urgency than ever, so we are better able to tackle the viruses that we will now inevitably be facing.