What is prevention in health?

An important role for the health and care system, and wider government, is to help people live longer and healthier lives by reducing the chance of illness in the first place, or preventing the progression of symptoms once people become ill. But different people mean different things by prevention – so here, we set out some of the different ways it is understood.

Every year, many people die sooner than they need to, or live with painful, distressing or disabling disease symptoms that could have been prevented.

In 2023, more than 1 in 8 deaths (13.9%) in England were considered preventable at the time of death – that’s 75,694 people. Examples of illnesses where a large proportion of deaths are preventable include heart disease, and lung, liver and skin cancers. And a higher proportion (the Department of Health and Social Care says more than half) of the total burden of disease, including years of life lived in poor health, is preventable. There are also unfair inequalities in preventable early deaths between those living in the richest and poorest areas of England.

It is widely agreed that prevention is important. Preventing ill health is a goal in and of itself as it can reduce sickness and early death. A focus on prevention has been shown to be effective – for example, government tobacco-control policies have been shown to reduce smoking, which in turn leads to fewer people developing tobacco-related illnesses such as lung or heart diseases. Preventing people getting sick, or preventing sickness getting worse, can also reduce demand on services that are increasingly under pressure. It could also bring wider economic benefit, as people are more able to contribute to society through employment or other activity. Many preventive interventions have also been shown to be cost effective; spending money on prevention now could ultimately mean needing to spend less on other services in future. Ultimately, shifting from a system focused on sickness to one focused on prevention is vital to improving health outcomes, and making the system more cost effective in the long term.

Yet people may mean different things by ‘prevention’. Prevention of what, and for whom? There are a wide range of different types of activity that can prevent ill health and promote good health, and a wide range of different actors who can undertake those activities – from urban planning that prioritises wellbeing, or an individual doing more physical activity to prevent heart disease, to a nurse administering a vaccination to prevent meningitis, a public health professional running a stop-smoking service, or employers funding health checks for their employees.

We have written this explainer because of the variety of conceptions of prevention. Different understandings between actors and sectors can mean that any activity may not be co-ordinated or optimal from a cost-effective population health perspective, or there may be gaps in activity, and generally, it’s much harder to make the case for prevention if there is no agreement on what it is or what it involves. Here we explain different types of prevention, highlighting some of the different ways it is understood, and what different services and stakeholders can do.

1. Types of prevention

Broadly defined, prevention is any action that keeps people healthy and prevents or avoids risk of ill health or death. Prevention can be classified further according to whether it focuses on whole populations or particular high-risk groups or individuals. It can also be classified according to at what point in the progression of a disease action is taken. Classifying and defining different types of prevention can seem somewhat academic, but if prevention is not clearly defined, it cannot be measured and we cannot know how much is happening.

When thinking about prevention, it’s helpful to think about how disease occurs without intervention. Diseases or health conditions are caused by a range of risk factors, which can be behavioural, social, economic, environmental or biological. Examples of risk factors include smoking, obesity, air pollution, stress and poverty. In turn, exposure to risk factors can lead to pathological changes in our bodies (sometimes called the subclinical stage of disease). For a long time, these might not lead to noticeable symptoms – ie, one might not feel any different – and so remain undetected. But eventually, they can lead to symptoms and clinical disease.

Prevention is sometimes classified into different ‘levels’, based on taking action at different points. Public health professionals and academics tend to think about the following levels:

• Primordial prevention – action to prevent exposure to risk factors in the first place. This tends to focus on population-wide interventions on a range of social determinants of health, such as poverty reduction, taxing unhealthy food, or ensuring access to parks or other green spaces for exercise or relaxation.

• Primary prevention – action to reduce exposure to risk factors, such as stopping smoking or weight management programmes, or to mitigate the impact of risk factors once exposure has occurred – for example, vaccinations to increase resistance to disease if exposure occurs.

• Secondary prevention – emphasises early disease detection by identifying disease before symptoms have progressed and stopping the disease worsening, if possible.

• Tertiary prevention – action to help people manage symptoms and prevent further disease progression once the disease has already developed. This can be thought of as harm reduction and helping people manage their disease. In this sense, certain types of health care treatment are a form of prevention.

This diagram gives examples of different types of prevention for lung disease:

For a larger version of this image please click here.

The levels of prevention framework originally comes from the field of public health. It has been around for many years and is often attributed to Leavell and Clark, two public health doctors working in the mid-20th century. However, primordial prevention is a relatively new concept compared with the other levels of prevention, as we have developed a better understanding of the impacts of the social determinants of health. It is still quite common for people to refer to primary prevention to mean both primordial and primary prevention (ie, action on social determinants to prevent exposure to risk, and action to manage risks for those already exposed).

The levels of prevention are not always clear-cut, as the boundaries of disease progression are also not clear-cut in practice. For example, high blood pressure can be considered both a risk factor for cardiovascular disease and a sign of subclinical disease. The National Institute for Health and Care Excellence suggests that statins – a type of medicine that lowers cholesterol – can be a form of primary prevention for heart disease for those with additional risk factors and a high chance of developing heart disease, or secondary prevention for those who have already been diagnosed with a cardiovascular disease.

Another point to note is that activity that might be considered one type of prevention for one population (such as secondary prevention in the form of postpartum depression screening for new mothers) might be primary prevention for another population (their children), since maternal mental health can have an impact on child development and child health.

As the levels of prevention are not always clear-cut, an alternative paradigm could be to think of any action to reduce risk factors (such as regulation of unhealthy things such as alcohol or sugary food and drinks) as primary prevention, and any action to slow down disease once exposed to risk (such as medical intervention or behavioural advice) as secondary prevention. This is the approach used by the Chief Medical Officer (CMO) and tends to be used in practice by the NHS – for example, in the 2023 CMO report on Health in an Ageing Society. This is an example, however, of how prevention terminology can be used differently by different people.

Preventing ill health or promoting good health?

In large part, prevention is concerned with risk factors, but the flipside of risk factors are protective factors that increase the likelihood of being in good health. Protective factors can include good nutrition, being in stable employment with a good income, living in good-quality housing, and having support networks. Prevention, particularly primary and primordial prevention, and action relating to preventing risk factors, can therefore not just be concerned with preventing ill health but also promoting good health and creating the conditions for health and wellbeing. Some people group ‘prevention’ and ‘health promotion’ together; others focus more on prevention only.

Prevention – for whom?

Targeted and universal approaches to prevention

Another way of thinking about prevention is to think about which groups or individuals are the focus of preventive interventions.

Efforts can be targeted at high-risk individuals or groups – people at greatest risk of developing a given condition. For example, diabetes prevention may prompt a focus on people with obesity – a major risk factor for diabetes. Alternatively, considerations may focus on more universal efforts over a much wider population. For diabetes prevention, that might look like a tax on products high in sugar.

Is one approach better than the other? Each has its strengths and weaknesses. Approaches targeting high-risk individuals may seem most effective, and interventions appropriate to the individual may help with motivation – ie, patients know the reason for the intervention and why it applies to them (eg, smoking cessation advice delivered to smokers). But finding those high-risk individuals may come with a cost – for example, it may require screening programmes.

Counterintuitively, population approaches may offer a larger benefit overall. Geoffrey Rose’s ‘prevention paradox’ outlines how preventive measures may not appear necessary or beneficial when considered at the individual level but at a population level may offer substantial public health benefits. For example, reducing levels of sugar in processed foods may offer a slight benefit for some individuals, but across a whole population, it could help prevent thousands of strokes or heart attacks.

Both targeted and universal strategies can work in tandem to bring about effective change.

Prevention over the life course

Physical and mental health and wellbeing are influenced by many factors over the life course, including a diverse range of social, economic and environmental factors such as diet, housing, social network, education, environment and childhood experiences, and risk factors such as smoking and drug and alcohol misuse. Taking a life-course approach to prevention considers the wider determinants that contribute to overall health and focuses on improving the conditions people are born into, live in and work in. This approach identifies key opportunities for minimising risk factors at different life stages, such as during pregnancy, early childhood, working age, and older age, recognising the interconnectedness of each stage.

Many lifelong illnesses and conditions are established in the early years of a person’s life, so this presents a key window for prevention of poor health outcomes, both in childhood and into adult life. Behaviours and patterns established in childhood can also set patterns and predispositions that can persist throughout the life course – for example, adverse childhood experiences can lead to increased risk of adult mental health issues. Healthy children are more likely to become healthy adults, and prevention of ill health in childhood brings both short-term and long-term benefits to society and the economy. It also reduces current and future health service costs.

Targeted prevention is specifically effective for children from low-income families. For example, Sure Start Children’s Centres led to fewer hospitalisations during childhood and adolescence, demonstrating how large-scale, holistic interventions can have a positive and lasting impact in improving children’s health.

2. Who does prevention?

Everyone has a role in preventing ill health and promoting good health – from different parts of the NHS and local government to almost all government departments. And it isn’t just the role of the government; the voluntary sector, employers, communities and individuals all have a role, too. However, different actors have different roles to play, and some roles are more clearly prevention focused than others.

The table below illustrates the range of different types of preventive activity different actors might undertake. (It is not an exhaustive list.) Traditionally, the NHS tends to undertake a lot of tertiary and secondary prevention, and may do less primordial prevention. Other actors, particularly local government and other government departments, may focus further upstream (ie, towards primary or primordial prevention) as they are better able to affect the socio-economic determinants of health.

It is important to note the distinction between the commissioning of prevention services and their delivery. For example, local government is often responsible for the commissioning and/or funding of prevention services that are delivered through different provisions (eg, through contracts with the NHS, or the voluntary, community and social enterprise (VCSE) sector). Responsibility for the commissioning of health visiting services lies with local authorities, and these services are provided by the NHS.

For a larger version of this table please click here.

3. Why is there not more of a focus on prevention?

There is strong evidence that a focus on prevention could improve the health of our population, and governments over the years have been enthusiastic about the potential of prevention. Yet action doesn’t seem to match rhetoric.

One issue is a lack of clarity and transparency as to what we mean by prevention, as noted earlier. Ambiguity means it can be used to characterise, or be the solution to, a range of different problems, and that ambiguity may lead to widespread support but minimal policy change. This also makes it difficult to account for preventive activity and a lack of transparency over spending. ONS data shows that only 5% of health care spending was on preventive activity in the most recent year for which data is available (2023). This funding was mainly distributed through the public health grant to local authorities, although the NHS also commissions some public health functions under Section 7A of the NHS Act 2006. But this does not cover the full range of preventive activity, including much of the secondary prevention undertaken by the NHS. In fact, a survey of NHS leaders by the Faculty of Public Health found that nearly three-quarters (73%) did not know how much they spent on prevention. Those who were able to answer the question felt that their budgets should be roughly doubled. Although money isn’t everything, it has a big impact – so if there is no transparent accounting framework for how much is being spent on prevention, it is unlikely that anyone will be held to account for cutting it.

Another issue is political. Spending is often focused on short-term, more acute goals, such as emergency care or the NHS waiting list. And the benefits of some prevention activities are more likely to occur in the medium term – outside of short-term budget considerations and political or electoral cycles. However, it must be noted that in other areas there is sometimes significant expenditure in the short term that may take several years to show results, which are not even guaranteed – for example, spending on NHS reorganisation or operational improvements.

Another related issue is that the benefits of prevention spending or activity may not accrue to the same actor who is undertaking it, which can lead to co-ordination problems or make it harder for relevant teams to make the case for investment. For example, local authorities might invest in weight management services, but the benefits in terms of reduced need for health care may accrue to the health system.

To prioritise prevention, there needs to be strong leadership. But the responsibility for prevention has shifted around. There has also been relatively recent reshaping at national level of where responsibility sits for national strategy and funding for prevention. Between 2013 and 2022, it was the responsibility of Public Health England (PHE) – whose abolition involved upheaval in leadership, institutional structure and service delivery. Various actors, including NHS England, the Department of Health and Social Care (Office for Health Improvement and Disparities), the UK Health Security Agency and local authorities now hold bits of PHE’s former functions, and it may not always be clear whose remit prevention is.

Ultimately, in order to truly shift to a more preventive system, there needs to be significant political will and focus at government, NHS and local levels. This will require better understanding and agreement over the different types of preventive activity that are beneficial and the roles different actors can play.