3.6.11Additional lessons
Vaccines and Immunity — IB Biology SL Revision Notes & Topical Questions
5 min read 5 parts Lesson 80 of 142
Curriculum Equation Key قوانين الرقم الهيدروجيني والاتزان الأيوني - pH & Acid-Base Equilibrium FormulasFast Exam Solution
pH = -log[H⁺] | pOH = -log[OH⁻] | pH + pOH = 14 | [H⁺][OH⁻] = 10⁻¹⁴
Word Equation & Conditions: الرقم الهيدروجيني = -لوغاريتم تركيز أيون الهيدروجين | pH + pOH = 14
Location & Specifications: الاتزان الأيوني، كيمياء 3 ثانوي، التحصيلي، و AP Chemistry.
Part 1 of 5What a Vaccine Contains
Antigens
- Antigens A vaccine supplies antigens, or DNA or RNA coding for antigens, so the body can respond without having the disease.
Live attenuated
- Live attenuated These contain weakened pathogens that can still multiply a little but cause little or no disease.
Inactivated
- Inactivated These contain killed pathogens, parts of pathogens or just the antigens alone.
Delivery
- Delivery Vaccines are given by injection into muscle or vein, or by mouth.
Part 2 of 5How Vaccination Gives Immunity
Vaccination produces active immunity because the person's own immune system makes the antibodies.
1
The vaccine introduces antigens, which are taken up by antigen-presenting cells.
2
Helper T cells activate specific B cells, which divide and form plasma cells.
3
Plasma cells secrete specific antibodies, which is the primary response.
4
Memory cells are formed and remain for years.
5
If the real pathogen later enters, memory cells give a faster, larger secondary response, so the person does not become ill.
Part 3 of 5Herd Immunity
Herd Immunity
Definition
- Definition If enough of a population is immune, the pathogen finds few susceptible hosts and cannot spread easily.
Protects others
- Protects others People who cannot be vaccinated, such as very young babies, are shielded by those around them.
Falling coverage
- Falling coverage If vaccination rates drop, outbreaks can occur because infected people meet more susceptible ones.
Eradication
- Eradication Smallpox was declared eradicated in 1980 after a worldwide vaccination programme.
Part 4 of 5Evaluating Evidence
Peer review
- Peer review Scientists publish findings so others can check methods and conclusions before ideas are accepted.
Media reports
- Media reports Reports of research may simplify results, so the original data should be checked.
Misinformation
- Misinformation Claims without evidence can reduce vaccination rates and put the whole population at risk.
| Immunity | Source of antibodies | Duration |
|---|---|---|
| Active (vaccine or infection) | Own plasma cells | Long-lasting |
| Passive (e.g. antibodies via milk) | Another individual | Short-lived |
Part 5 of 5Exam Checklist & Tips
3.6.11 – Key Points for the Exam
- Vaccine A preparation of antigens that stimulates immunity without causing disease.
- Memory cell A long-lived lymphocyte that responds rapidly to re-exposure.
- Herd immunity Protection of a population when a large proportion is immune.
- Attenuated Weakened so that it is unlikely to cause disease.
Common Mistakes
- Saying that a vaccine contains antibodies; it contains antigens.
- Writing that vaccines give instant protection, when memory cells take time to form.
- Thinking herd immunity requires every person to be vaccinated.
- Mixing up active and passive immunity.
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