Vaccination

VaccinationSpec 4.3.1.7

Vaccination involves introducing small quantities of dead or inactive forms of a pathogen into the body. This stimulates the white blood cells to produce antibodies.

How it protects an individual

1. A vaccine containing dead or inactive pathogen is given.
2. The white blood cells are stimulated to produce antibodies.
3. If the same pathogen re-enters the body later, the white blood cells respond quickly to produce the correct antibodies.
4. The pathogen is destroyed, preventing infection and illness.

How it protects a population

If a large proportion of the population is immunised, the pathogen cannot spread easily because most people it reaches are protected. People who have not been vaccinated are less likely to come into contact with an infected person. This is sometimes called herd immunity.

Evaluating the global use of vaccination

You may be given data, such as the number of cases of a disease against the percentage of people vaccinated, and asked to evaluate. Describe the trend, then link it to the idea above: more people vaccinated means fewer cases.

• Benefit: prevents illness in individuals and reduces the spread of disease through the population.
• Benefit: protects even people who have not been vaccinated, if enough people are immunised.
• Limitation: it is only effective if a large proportion of the population is immunised.
• Limitation: if the proportion of people vaccinated falls, the disease can spread again and cases rise.

You do not need to know vaccination schedules or the side effects of specific vaccines.