We’re soon going to have to make our own choices about social distancing, wearing masks and travel. When the legal enforcement of rules is lifted, the way in which each of us deals with the risk of Covid-19 will be down to personal judgment. But how well equipped are we to make these decisions?
Graphs and data can help explain things, but what’s also needed is a deep understanding of how science works, and, perhaps most important of all, a sense of how to weigh up the odds of coming down with the disease and how it might affect us. Not in an abstract way, but in our day-to-day lives. And what many people don’t realise is that Covid-19 is just the start.
Very soon, we will be exposed to all kinds of complicated information about the state of our health, including our personal level of risk for any number of illnesses. More and more, we will have to make decisions, based on new science, about almost every aspect of our lives.
This is because progress in human biology is accelerating at an unprecedented rate, and there’s no sign of it slowing down. On the horizon are entirely new ways of defining, screening and manipulating health, completely new insights about diet, and any number of ideas for how babies can be born. Things are not moving along incrementally. Rather, we are on the brink of a revolution.
We’re used to thinking about cancer, for instance, in terms of a simple list of things to do or not do. Don’t smoke, do use sunscreen, eat more or less of this or that type of food. But as a result of ever more detailed analysis of our bodies, we will increasingly need to think about this and any number of other diseases in a different way: in terms of the probability of their occurrence.
Each of us is unique, a combination of attributes arising from our genes and upbringing, as well as what we eat, when we eat, how much we sleep, exercise or get stressed, our exposure to pollutants, pollen and bacteria, and myriad other influences. But for all this profound individuality, there is also a finite set of recurring patterns that can be used to analyse our health. To take a familiar example: the idea of the body-mass index, a value derived from a person’s weight and height. This is used to categorise us as underweight, normal weight, overweight or obese. It’s useful as it indicates an increased risk of health problems such as type 2 diabetes, and steps can be taken to reduce the likelihood of this occurring.
But the advent of more advance metrics lead us into a sea of more nuanced probabilities. For instance, consider the Human Cell Atlas – a huge global project in which more than 10,000 scientists have come together to identify and classify all 37 trillion cells of the human body. By comparing individual cells in depth – by analysing the level to which genes are activated in them, how many copies of each protein is present in them, and so on – we can classify single cells with unprecedented detail. This will lead to a deeper understanding of the way in which tissues and organs are constructed, which cells derive from which other cells in the body and what goes wrong in disease. But this will also enable deep analytics of the body’s cells in a biopsy, blood sample or even a nasal swab.
Currently a person’s health is often assessed by a blood count – a simple record of how many platelets, red or white cells are present. But building on the Human Cell Atlas and related research, we will be able to examine in great detail the types, status and history of a person’s blood cells. This is especially important for white blood cells, a catch-all term for countless different types of immune cells, which we already know can vary hugely between people.
For instance, the state of a person’s immune system correlates with the symptoms a person is likely to have if infected with Sars-COV2. Markers of immune activity also correlate with a person’s mental health. One recent analysis concluded that particular pro-inflammatory secretions from immune cells (called cytokines) are found at higher levels in people who are depressed. So as we learn about the composition and status of the body’s immune cells, this will inevitably establish new ways of assessing health.
To take another example, one analysis showed that all sorts of immune cells are important in the construction of a placenta. What they all do isn’t yet clear – this is at the cutting edge of knowledge. But in the future we may well be able to use that information to detect portents of a problem in pregnancy before it occurs.
The composition of a person’s gut microbiome – in other words, the bacteria found in faeces – is now beginning to give up all sorts of information about our health. An analysis of the microbiome in cancer patients, for instance, can help predict the chance that a particular type of immune therapy is likely to work. And in one small study, gut microbes from patients with metastatic melanoma who had responded to a particular therapy could be transplanted into patients who were refractory to treatment, and help some of them respond, too.
Recently, a consortium of researchers from 744 different research centres reported the genetic sequence of more than 2,600 cancer samples. It was found that each person’s cancer contained four or five “driver mutations” – changes to the genome that promote cancer directly by endowing cells with a special ability to multiply. Many other mutations that don’t drive the cancer directly but accompany it were found to occur in patterns that could be used diagnostically. Crucially, several mutations were calculated to occur long before any clinical diagnosis of cancer would be apparent: secret messages inside our cells, tell-tale signs of cancer beginning.
So how are we to act on all this new information? How do we grapple with a test result that means your risk of developing cancer, or another illness, within the next 20 years is one in six? Would it be different if it was one in four? How about within five years instead of 20? At what point would you decide to take a medicine as a precaution, or undergo a preventive operation, knowing that the medication or operation carries its own risks?
Science is often perceived as bringing us exactness and precision, which of course it does in many ways. But the deeper we look at life – and especially the human body – the more we find that precise definitions become hard. Instead we are fundamentally dynamic and plastic. Everything is in flux, our health balanced on a tightrope – which is why a lot comes down to risk and probabilities. And these are very hard to act on.
There’s something even trickier to consider: a whole host of new ways to categorise us as either normal or abnormal are going to arise. Everyone falls short in some way if enough things are measured. There are obvious implications here for health insurance premiums but just as importantly for our psychological wellbeing: being categorised as having this or that risk or flaw can be deeply troubling, both for an individual person’s sense of self and for society’s view of human diversity.
To equip us for all this, we need to reach a new level of public understanding about health, disease, risk and probability. Some of this should be taught in schools, colleges and universities, of course, but there needs to be more. During the pandemic, we have seen a huge increase in the number of scientists discussing their work in public. Now, as the UK government formally lifts restrictions, we must not retreat from this exposure. Rather, we must embrace science as a vital part of our culture even more than we do now. At stake is not just our health and wellbeing, but our sense of what it means to be human.