Primary prevention and primary interventions
Primary prevention stops disease before it starts, by reducing exposure to risk factors or by increasing resistance to disease (as vaccination does by preparing the immune system).
Remember
Primary prevention acts before disease develops, by reducing exposure to risk factors or increasing resistance, and vaccination is a classic example.
Primary prevention acts before any disease has started. Its aim is to stop new illness appearing, either by reducing exposure to risk factors (the things that raise the chance of disease) or by increasing resistance to disease. Because it works before the disease process begins, it reduces incidence, the number of new cases appearing in a population over time.
Vaccination prepares the immune system before exposure, which makes a future infection less likely to take hold. Primary interventions prevent the onset of disease by four main methods:
- Immunisation, such as routine childhood vaccination.
- Avoiding contact with environmental risk factors, for example using bug spray against mosquito bites.
- Taking precautions regarding communicable (infectious) disease, such as wearing condoms to prevent sexually transmitted diseases.
- Reducing health-related behaviour risk factors, for example helping people who are well to stop smoking.
Primary prevention is the first of three levels, and secondary prevention sits after it on the disease timeline. Secondary prevention finds and treats disease early, as in screening. Tertiary prevention limits the complications and disability of disease that is already established, such as rehabilitation (helping a person regain function) after a stroke. To tell the levels apart, ask when the action takes place on the disease timeline: before disease, early in its course, or once harm has been caused.
Where advice sits among the levels depends on whether the person already has disease. Stopping smoking is primary prevention in someone who is well, but tertiary in a person who already has a smoking-related condition, so the thing to check first is whether the person already has the disease.
Key facts
- Aim
- to prevent disease from occurring by reducing exposure to risk factors or by increasing resistance to disease.
- Timing
- it acts before disease starts, so it protects healthy people.
- Effect on incidence
- it reduces the number of new cases appearing in a population over time.
- Secondary or tertiary
- secondary prevention finds disease early, as in screening, while tertiary prevention limits the effects of disease that is already established.
- Same advice, different level
- stopping smoking is primary prevention if the person is well and tertiary if disease is established.
- HPV vaccination
- reduces the chance of getting human papillomavirus (HPV), a virus spread through skin contact, usually when having sex. The vaccine covers nine HPV types, but more types are linked to cervical cancer, so it does not remove the need for screening.
Exam traps
- Screening adults who have no symptoms is not primary prevention, because it detects disease that may already have begun, which makes it secondary prevention.
- Statins given after a heart attack to reduce the chance of further events are not primary prevention, because the person already has established disease. In the three-level public health framework this is tertiary prevention, although cardiology (heart medicine) guidelines call it secondary prevention, meaning prevention of further events.
- Primordial prevention, a further level that some authors add to the classic three, does not fit a person who already smokes: it aims to stop a risk factor appearing in the first place, but the risk factor is already present.
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