Vaccination

Question 1

What is a vaccination?

Answer 1

1. Injection of antigens
2. From attenuated (dead or weakened) pathogens
3. Stimulates the formation of memory cells
4. A vaccine can lead to symptoms because some of the pathogens might be alive / active / viable; therefore, the pathogen could reproduce and release toxins, which can kill cells

Question 2

Explain how the use of vaccines can provide protection for individuals against disease:

Answer 2

1. Normal immune response but the important part is that memory cells are produced
2. On reinfection / secondary exposure to the same antigen, the secondary response therefore produces antibodies faster and at a higher concentration
3. Leading to the destruction of a pathogen/antigen (e.g. agglutination and phagocytosis) before it can cause harm / symptoms = immunity

Question 3

Explain how the use of vaccines can provide protection for populations against disease (herd immunity):

Answer 3

1. Large proportion but not 100% of population vaccinated against a disease – herd immunity
2. Makes it more difficult for the pathogen to spread through the population because…
3. More people are immune so fewer people in the population carry the pathogen / are infected
4. Fewer susceptible so less likely that a susceptible / non-vaccinated individual will come into contact with an infected person and pass on the disease

Question 4

Active Immunity:

Answer 4

1. Initial exposure to antigen.
2. Memory cells in involved.
3. Antibody is produced and secreted by plasma cells.
4. Slow takes time to develop.
5. Long term immunity (antibody can be produce in a response to a specific again).

Question 5

Passive Immunity:

Answer 5

1. No exposure to antigen.
2. No memory cells involved involved.
3. Antibody introduced into body from another organism e.g. breast milk/ across the placenta.
4. Fast acting.
5. Short term immunity (antibody broken down).

Question 6

Describe some of the ethical issues associated with the use of vaccines:

Answer 6

1. Tested on animals before use on humans → animals have a central nervous system so feel pain (some animal based substances are also used to produce vaccines)
2. Tested on humans → volunteers may put themselves at unnecessary risk of contracting the disease because they think they’re fully protected e.g. HIV vaccine so have unprotected sex → vaccine might not work
3. Can have side effects
4. Expensive – less money spent on research and treatments of other diseases

Question 7

How does antigen variability create difficulties for effective vaccinations?

Answer 7

1. New vaccines against a disease need to be developed more frequently e.g. influenza
2. Vaccines against a disease may be hard to develop or can’t be developed in the first place e.g. HIV.
3. May experience a disease more than once e.g. common cold

Question 8

Explain the effect of antigen variability on disease:

Answer 8

1. Change in antigen shape (due to a genetic mutation)
2. Not recognised by B memory cell → no plasma cells / antibodies
3. Not immune
4. Must re-undergo primary immune response → slower / releases lower concentration of antibodies
5. Disease symptoms felt

Question 9

Explain the effect of antigen variability on disease prevention (vaccines):

Answer 9

1. Change in antigen shape (due to a genetic mutation)
2. Existing antibodies with a specific shape unable to bind to changed antigens / form antigen-antibody complex
3. Immune system i.e. memory cells won’t recognise different antigens (strain)

Question 10

Evaluate methodology relating to the use of vaccinations:

Answer 10

1. A successful vaccination programme:
2. Produce suitable vaccine
3. Effective – make memory cells
4. No major side effects → side effects discourage individuals from being vaccinated
5. Low cost / economically viable
6. Easily produced / transported / stored / administered
7. Provides herd immunity

Question 11

Evaluating a conclusion that’s been made from a set of data / study:

Answer 11

1. If there is a scatter graph, the relationship between two variables may be a positive / negative correlation, or no correlation
2. But correlation between two variables doesn’t always mean there’s a causal relationship – correlation could be due to change or another variable / factor
3. Repeatability (when an experiment is repeated using the same method and equipment and obtains the same results)
4. Have there been other experiments / studies showing the same?
5. Validity (suitability of the investigative procedure to answer the question being asked)

Question 12

Evaluate evidence and data relating to the use of vaccinations :

Answer 12

1. Does the data answer the question set out to investigate?
2. Example: research project on potential vaccines to protect people against HIV used monkeys and a virus called SIV (which only infects monkeys and causes a condition similar to AIDS in them) .
3. Scientists have questioned the value of the research because there may be differences between human and money responses / immune systems, and a vaccine developed against SIV may not work against HIV / may be (significant) differences between SIV and HIV
   - Potential bias?