Preventing the Spread of Disease | Biology for GCSE/IGCSE - Year 11 PDF Download

Preventing the Spread of Disease: Extended

• When a significant portion of the population is vaccinated, it shields the entire community from widespread infection because there are limited opportunities for the pathogen to propagate—it can only do so if it infiltrates the body of an unvaccinated individual.
• This protective phenomenon is termed herd immunity.
• However, if vaccination rates decline within a population, it exposes the remaining individuals to heightened risks of widespread infection, as they are more likely to encounter contagious, infected individuals. This escalation in infections amplifies the likelihood of fatalities stemming from a particular infectious disease.

Herd Immunity

• Herd immunity is a crucial concept that prevents epidemics and pandemics from spreading within populations.
• Herd immunity plays a vital role in preventing the widespread occurrence of diseases within a community.
• It is achieved when a significant portion of the population becomes immune to a disease, either through vaccination or prior illness, making it difficult for the disease to spread.
• By immunizing a large number of individuals, especially children who are more susceptible, the entire community benefits from reduced disease transmission.
• Vaccination programs are designed not only to control diseases but also to eradicate them completely in some cases.
• An excellent example of successful disease eradication through vaccination is smallpox, which was officially declared eradicated in 1980 thanks to a global vaccination campaign led by the World Health Organization.

Key Points

• Herd immunity prevents epidemics and pandemics by increasing immunity levels in the population.
• Vaccination of children is crucial for maintaining herd immunity as they are regularly in contact with others and can easily spread diseases.
• Vaccination programs aim not only to control but also to eradicate dangerous diseases like smallpox.