Biology 6.6 Vaccination

Immunity = the ability of an organism to resist infection, two forms:

• Passive immunity = produced by introduction of antibodies into individuals from an outside source. Antibodies aren't produced by individuals themselves, not replaced when they are broken down in the body so immunity is normally short-lived.
• Active immunity = produced by simulating production of antibodies by the individuals own immune system - normally long-lasting.

Vaccination = introduction of a substance into the body with the intention of stimulating active immunity against a particular disease.

Carried out on a large scale = provides protection for individuals and population.

Features of a successful vaccination programme

• Suitable vaccine = economically available in sufficient quantities to immunise vulnerable population.
• Few side effects which may discourage individuals in population from being vaccinated.
• Means of storing, producing and transporting vaccine available = using technologically advanced equipment, hygienic conditions and refridgerated transport.
• Means of adminstering vaccine properly at appropriate time = training staff with appropriate skills at different centres throughout population.
• Possible to vaccinate vast majority of vulnerable population - best done at time that for a certain period there are no individuals with the disease so transmission of pathogen is interrupted = herd immunity.

Why vaccination doesn't eliminate a disease

• Vaccination fails to induce immunity in certain individuals e.g. people with defective immune systems.
• Individuals may develop the disease immediately after vaccination before their immunity levels…