Vaccination
Laura Armstrong & Joe Wolfensohn
Teachers
Contents
Recall Questions
This topic requires prior knowledge of the role of white blood cells in defending the body against pathogens.
What are antigens?
Specific molecules on the surface of a pathogen
What is the role of antibodies in the immune system?
Antibodies bind to antigens on pathogens, helping to destroy them or mark them for destruction
What type of cell produces antibodies?
A white blood cell (known as a lymphocyte)
Topic Explainer Video
Check out this @JoeDoesBiology video that explains vaccinations, then read the study notes. Once you’ve gone through them, don’t forget to try the practice questions!
Vaccination
What is Vaccination?
- Vaccination is a method of preventing illness by preparing the immune system.
- A vaccine is a small amount of dead or inactive pathogen that is injected into the body.
- These do not cause disease, but the antigens stimulate white blood cells to produce antibodies and become memory cells.
How Vaccination Works:
- Dead or inactive pathogens are introduced via a vaccine.
- White blood cells detect the antigens and produce specific antibodies.
- The antibodies will bind to the antigens and destroy the pathogens.
- Some of these white blood cells become memory cells.
- If the same pathogen enters the body again:
-
- Memory cells quickly produce the correct antibodies in large quantities and for longer.
- The pathogen is destroyed before it can cause illness.
Graph showing the number of measles antibodies after vaccination and after a subsequent infection with the virus.
Herd Immunity:
- Herd immunity is when a large percentage of the population is vaccinated.
- This means fewer people are infected so won't spread the pathogen.
- Some people can't be vaccinated, due to other health conditions, herd immunity helps to protect them and reduce the spread of the pathogen to them.
Evaluation of Vaccinations
Pros (Benefits)
- Prevent disease: Vaccines protect individuals from serious infections like measles, polio, or HPV.
- Herd immunity: If enough people are vaccinated, it reduces the spread of disease - even protecting unvaccinated people.
- Eradicate diseases: Some diseases (e.g. smallpox) have been wiped out thanks to global vaccination.
- Cost-effective: Preventing illness is cheaper than treating it in the long-term.
Cons (Limitations)
- Side effects: Some people may have mild side effects (e.g. swelling or fever). Severe side effects are extremely rare.
- Injections: A small number of people are scared of needles and may worry about them being painful or causing infection.
- Need for boosters: Some vaccines wear off and need booster shots (e.g. tetanus).
- Public resistance: Misinformation can cause people to avoid vaccines, reducing their effectiveness in communities.
Key Terms and Definitions
|
Term |
Definition |
|
Vaccine |
A substance containing dead or inactive pathogens used to stimulate antibody production. |
|
Antigen |
A protein on the surface of a pathogen that triggers an immune response. |
|
Antibody |
A protein produced by lymphocytes that binds to antigens on pathogens. |
|
Memory cell |
A type of white blood cell that "remembers" how to make a specific antibody, giving immunity. |
|
Herd immunity |
When a large proportion of the population are immune to a pathogen. |
No answer provided.
Exam Tip
- Use the correct sequence of events in your answers: vaccine → white blood cells → antibodies → memory cells → faster antibody production.
- Make sure to say ‘white blood cells produce antibodies’ and not just ‘the body produces antibodies’.
No answer provided.
Practice Question
Explain how vaccination prevents illness in an individual. (4 marks)
Model Answer:
- Vaccines contain small amounts of dead or inactive pathogens.
- These stimulate white blood cells to produce specific antibodies, which destroy the pathogen.
- Some white blood cells become memory cells.
- If the pathogen re-enters, the body rapidly produces the correct antibodies in large quantities, and for longer, to destroy it before illness occurs.
More Practice
Try to answer the practice question from the TikTok video on your own, then watch the video to see how well you did!