What is a vaccination?
- Injection of antigens
- From attenuated (dead or weakened) pathogens
- Stimulates the formation of memory cells
- 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
Explain how the use of vaccines can provide protection for
individuals against disease
- Normal immune response but the important part is that memory cells are produced
- On secondary exposure to the same antigen, the
secondary response therefore produces antibodies faster and at a higher concentration - Leading to the destruction of a pathogen before it can cause harm = immunity
Explain how the use of vaccines can provide protection for
populations against disease (herd immunity)
Large proportion but not 100% of population vaccinated against a disease – herd immunity
- Makes it more difficult for the pathogen to spread through the population because
- More people are immune so fewer people in the population carry the pathogen / are infected
- Fewer susceptible so less likely that a susceptible / non-vaccinated individual will come into contact with an infected person and pass on the disease
Active immunity
Active immunity
-initial exposure to antigen
-memory cells involved
-Antibody is produced and secreted by plasma cells
-slower as it takes time to develop
-Long term immunity as antibody can be produced in response to a specific antigen again
Passive immunity
-no exposure to antigen and no memory cells involved
-Antibody produced from another organism, e.g.breastmilk from mother
-fast acting
-short term immunity as antibodies broken down
Describe some of the ethical issues associated with the use of
vaccines
- Tested on animals before use on humans → animals have a central nervous system so feel pain
- Tested on humans → volunteers may put themselves at unnecessary risk of contracting the disease because they think they’re fully protected → vaccine might not work
- Can have side effects
- Expensive – less money spent on research and treatments of other diseases
Explain the effect of antigen variability on disease prevention
- Change in antigen shape (due to a genetic mutation)
- Not recognised by B memory cell → no plasma cells / antibodies
- Not immune
- Must re-undergo primary immune response → slower / releases lower concentration of antibodies
- Disease symptoms felt
Evaluate methodology relating to the use of vaccinations
A successful vaccination programme:
- Produce suitable vaccine
- Effective – make memory cells
- No major side effects → side effects discourage individuals from being vaccinated
- Low cost / economically viable
- Easily produced / transported / stored / administered
- Provides herd immunity
