2.4 Vaccination

Question 1

What is immunity?

Answer 1

The ability of an organism to resist infection by protecting against disease-causing microorganisms or their toxins that invade their bodies. It involves the recognition of foreign material (antigens)

Question 2

What is passive immunity?

Answer 2

• Produced by the introduction of antibodies into individuals from an outside source.
• No direct contact with the pathogen or its antigen is necessary to induce immunity. Immunity is acquired immediately.
• As the antibodies are not being produced by the individuals themselves, the antibodies are not replaced when they are broken down, no memory cells are formed and so there is no lasting immunity.

Question 3

What is active immunity?

Answer 3

• Produced by stimulating the production of antibodies by the individuals’ own immune system.
• Direct contact with the pathogen or its antigen is necessary.
• Immunity takes time to develop. It is generally long-lasting and is of two types

Question 4

What are the 2 types of active immunity?

Answer 4

• Natural active immunity
• Artificial active immunity

Question 5

What is natural active immunity?

Answer 5

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

Question 6

What is artificial active immunity?

Answer 6

Forms the basis of vaccination (immunisation). It involves inducing an immune response in an individual, without them suffering the symptoms of the disease.

Question 7

How does vaccination work?

Answer 7

• Vaccination is the introduction of the appropriate disease antigens into the body, either by injection or by mouth.
• The intention is to stimulate an immune response against a particular disease. The material introduced is called vaccine and, in whatever form it contains one or more types of antigen from the pathogen.
• These antigens stimulate the primary immune response
• The response is slight because only a small amount of antigen has been introduced, However, the crucial factor is that memory cells are produced and remain in the blood and so secondary response is rapid and produces higher concentration of antibodies and the pathogen is destroyed before it causes symptoms
• When carried out on a large scale, this provides protection against disease not only for individuals, but also for whole populations.

Question 8

What are some examples of passive immunity?

Answer 8

• Examples of passive immunity include anti-venom given to the victims of snake bites and the immunity acquired by the foetus when antibodies pass across the placenta from the mother.

Question 9

Compare passive and active immunity. Give examples of both types

Answer 9

• both involve antibodies
• can be natural or artificial
passive natural - antibodies in breast milk/across placenta
passive artificial - anti-venom, needle stick injections
active natural - humoral response to infection
active artificial - vaccination

Question 10

Contrast passive and active immunity.

Answer 10

Passive: no memory cells and antibodies not replaced when broken down=short term
Active: memory cells produced=long term

Passive: immediate
Active: time lag

Passive: antibodies from external source
Active: lymphocytes produce antibodies

Passive: direct contact with antigen not necessary
Active: direct contact with antigen necessary

Question 11

What is herd immunity?

Answer 11

Vaccinating large proportion of population reduces available carriers of the pathogen
Protects individuals who have not been vaccinated e.g. those with a weak immune system

Question 12

What are some ethical issues surrounding the use of vaccines?

Answer 12

• production may involve use of animals
• potentially dangerous side-effects
• clinical tests may be fatal
• compulsory vs opt-out