Vaccine-Preventable Diseases
Within immunization practice, vaccine-preventable diseases are the infectious diseases for which routine vaccination can prevent infection, severe illness, or onward transmission. This area orients the reader to the family of conditions addressed by immunization programmes and to the shared logic of prevention that links them, before the individual disease topics give the detail.
Definition
Vaccine-preventable diseases are communicable diseases for which a licensed vaccine can induce protective immunity, reducing the incidence of infection or severe disease in vaccinated individuals and, where coverage is high, reducing transmission across a population.
Scope
The area gives a brief orienting overview of vaccine-preventable diseases as a group: why they are grouped together, the common principle that vaccination primes adaptive immunity ahead of natural exposure, and how immunization at the population level reshapes the epidemiology of these infections. It collects the individual disease topics rather than giving clinical schedules or recommendations.
Sub-topics
Core questions
- What unites the diseases addressed by routine immunization programmes?
- How does vaccination change the burden of these diseases at the population level?
- Why do some controlled diseases resurge when vaccine coverage falls?
Key concepts
- Adaptive immunity and immunologic memory
- Correlates of protection
- Herd immunity
- Vaccine coverage and resurgence
- Vaccine confidence and hesitancy
- Elimination and eradication
Mechanisms
Each disease in this area is preventable because a vaccine can present the immune system with antigens from the responsible pathogen, generating adaptive immunity and immunologic memory so that a later natural exposure is met with a faster and stronger response. The immune markers that predict this protection are termed correlates of protection (Plotkin, 2013). When a sufficiently large share of a population is immune, transmission chains are interrupted and unvaccinated individuals gain indirect protection, the basis of herd immunity. Sustaining these effects depends on maintaining coverage, which in turn depends on public confidence in vaccines (Larson et al., 2011).
Clinical relevance
Grouping diseases by their preventability through vaccination highlights how immunization changes the epidemiology of infection and frames the evidence used to appraise immunization programmes. This area is educational and descriptive; it is not a vaccination schedule and is not a basis for individual medical decisions.
Epidemiology
Immunization against the diseases in this area has produced some of the largest reductions in infectious-disease burden in public health, including the global eradication of smallpox and steep declines in measles and polio where coverage is high. Where coverage falls or confidence erodes, previously controlled diseases such as measles and pertussis can resurge (Larson et al., 2011).
History
Vaccination grew from the eighteenth-century practice of inducing protection against smallpox into a programme covering many major pathogens during the twentieth century, culminating in the eradication of smallpox. Subsequent work formalised the immunologic correlates that underlie protection and the population effects of immunization, while the social determinants of vaccine uptake have become a recognised challenge to sustaining control (Plotkin, 2013; Larson et al., 2011).
Debates
- How should vaccine confidence be sustained?
- Keeping vaccine-preventable diseases under control depends not only on vaccine performance but on public trust; the determinants of confidence and the most effective ways to strengthen it remain an active area of study and policy.
Key figures
- Stanley Plotkin
- Heidi Larson
Related topics
Seminal works
- plotkin-2013
- larson-2011
Frequently asked questions
- What makes a disease vaccine-preventable?
- A disease is vaccine-preventable when a vaccine can prime the immune system to recognise the responsible pathogen and mount a protective response, lowering the chance of infection or severe illness. Routine immunization programmes are built around such diseases.
- Why do vaccine-preventable diseases sometimes return?
- When vaccine coverage in a population falls below the level needed to interrupt transmission, a previously controlled disease can resurge. Declining coverage is often linked to gaps in vaccine confidence.