Vaccination Flashcards
Describe the nature of vaccines
Vaccines are materials that contain one or more antigens from the pathogen
Whats 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
Passive immunity
-produced by introduction of antibodies into individuals from outside source
-NO direct contact with pathogen/ its antigen necessary to induce immunity
Why is passive immunity NOT long lasting?
as no B-cells are involved in the production of antibodies and therefore no memory cells are formed. When the antibodies are broken down they can not be replaced again.
Active immunity
produced by stimulating production of antibodies by individual’s own immune system
-direct contact with pathogen/its antigen is necessary
-immunity takes time to develop + generally long lasting
What are the 2 types of active immunity
artificial active and natural immunity
natural immunity
-results from an individual becoming infected with disease under normal circumstances
-body produces its own antibodies
Artificial active immunity
-forms from basis of vaccination
-involves inducing immune response in an individual, without them suffering symptoms of disease
What are 5 features that make a successful vaccination programme?
-there must be sufficient quantities available in or order to vaccinate large populations (considered economically)
-there must be appropriate means to produce, transport and store large quantities of the vaccine
-it should have minimal side effects so enough people are willing to be vaccinated
-there must be a suitable way to distribute the vaccination, with well-trained administrators
-it must be possible to vaccinate the majority of the vulnerable population (to produce herd immunity)
Use of vaccines to produce protection for individuals against disease
- Normal immune response but the important part is that memory cells are produced
- On reinfection / 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/antigen (e.g. agglutination and phagocytosis)
before it can cause harm / symptoms = immunity
The use of vaccines to 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
Differences between active and passive immunity
Active immunity
-Initial exposure to antigen e.g. vaccine or primary infection
-Memory cells involved
-Antibody is produced and secreted by (B) plasma cells
-Slow; takes time to develop
-Long term immunity→antibody can be produced in response to a specific antigen again
passive immunity
-No exposure to antigen
-No memory cells involved
-Antibody introduced into body from another organism e.g. breast milk / across placenta from mother
-Fast acting
-Short term immunity (antibody broken down)
Explain why vaccination rarely eliminates a disease
- vaccination does not cause immunity in some individuals
- individuals develop disease immediately after vaccination before immunity is reached> individuals may harbour pathogen and reinfect others
- pathogen mutates so vaccines no longer cause effective immunity > new antigens on pathogen no longer recognised by immune system> immune system doesn’t produce antibodies to destroy pathogen> antigenic variability
- many varieties of a pathogen so impossible to develop vaccine to all
- some people may be against vaccination for religious, ethical or medical reasons
-certain pathogens ‘hide’ from body’s immune system > conceal themselves inside cells/ live in places out of reach eg within intestines
Ethics of vaccines
- 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
- Evaluating a conclusion that’s been made from a set of data / study
- If there is a scatter graph, the relationship between two variables may be a positive / negative correlation, or no correlation
- But correlation between two variables doesn’t always mean there’s a causal relationship – correlation could be due to change or another variable / factor- Repeatability (when an experiment is repeated using the same method and equipment and obtains the same results)
- Have there been other experiments / studies showing the same?
- Validity (suitability of the investigative procedure to answer the question being
asked)
- Does the data answer the question set out to investigate?
- 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) . 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?
Describe how a vaccination leads to the production of antibodies
-Vaccine contains antigen from pathogen
-Phagocyte presents antigen on cell-surface membrane
-T-cell with complementary receptor binds to antigen
-T-cell stimulate B-cell (with the complementary antibody)
-B-cell secretes a large amount of antibodies and clones itself, all clones produce the same antibody
