5.6 Vaccination

Question 1

Define immunity

Answer 1

the ability of an organism to resist infection

Question 2

What are the 2 main types of immunity?

Answer 2

1. Passive immunity

2. Active immunity (+ natural active immunity, +artificial active immunity)

Question 3

Define passive immunity

Answer 3

resistance to disease that is acquired from the introduction of antibodies from another individual, rather than an individuals own immune system. (as antibodies are not produced by individual, the antibodies are not replaced when they are broken down, no memory cells are formed so theres no lasting immunity)

Question 4

Define active immunity

Answer 4

resistance to disease resulting from the activities of an individuals own immune system whereby an antigen induces plasma cells to produce antibodies.

Question 5

Define natural active immunity

Answer 5

results from an individual becoming infected with a disease under normal circumstances. They body produces its own antibodies and may continue to do so for many years

Question 6

Define artificial active immunity

Answer 6

forms the basis of vaccination immunisations. It involves inducing an immune response in an individual, without them suffering the symptoms of the disease

Question 7

Define vaccination

Answer 7

the introduction of a vaccine containing appropriate disease antigens into the body, by injection or mouth, in order to induce artificial immunity.

Question 8

What is the main benefit of vaccination?

Answer 8

Memory cells are produced. These remain in the blood and allow a greater, and more immediate, response to a future infection with the pathogen.

Question 9

What are features of a successful vaccination programme?

Answer 9

1. economically available in sufficient quantities to immunise most of the vulnerable population
2. few side effects
3. means of producing, storing and transporting the vaccine must be available
4. must be means of administering the vaccine properly at the appropriate time
5. must be possible to vaccinate the vast majority of the vulnerable population to produce herd immunity

Question 10

What is herd immunity?

Answer 10

When a sufficiently large proportion of the population has been vaccinated to make it difficult for a pathogen to spread within that population.

Question 11

Why might vaccination not eliminate a disease?

Answer 11

1. vaccination fails to induce immunity in certain individuals
2. individuals may develop the disease immediately after vaccination but before their immunity levels are high enough to prevent it. These individuals may harbour the pathogen and reinfect others
3. the pathogen may mutate frequently so that its antigens change suddenly rather than gradually. Meaning that vaccines suddenly become ineffective because the new antigens on the pathogen are no longer recognised by the immune system. The immune system doesn’t produce the antibodies to destroy the pathogen
4. impossible to develop a vaccine thats effective against all varieties of a particular pathogen
5. certain pathogens ‘hide’ from the body’s immune system, either by concealing themselves inside cells, or by living in places out of reach
6. individuals may have objections to vaccination for certain reasons.

Question 12

Define antigenic variability

Answer 12

mechanism by which an infectious agent e.g bacterium/virus alters the proteins or carbs on its surface and thus avoids a host immune response