This exam focus covers Exam Focus within Vaccination and Herd Immunity for GCSE Biology. How vaccines work, types of vaccines, population immunity, vaccination programs It is section 13 of 15 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
Topic position
Section 13 of 15
Practice
18 questions
Recall
21 flashcards
Exam Focus
Very Frequently ExaminedVaccination and herd immunity appear in AQA Paper 2 almost every year, often as a 4-6 mark extended response. The topic frequently combines biology with data interpretation and ethical discussion.
- How vaccines work (4-5 marks): Vaccine introduces antigens → activates B cells → clonal expansion → plasma cells produce antibodies → memory B cells formed → rapid secondary response on real exposure. Must include "memory cells" to earn full marks.
- Herd immunity explanation (3-4 marks): When a high proportion of the population is immune, even unvaccinated individuals are protected because the pathogen cannot spread efficiently. Explain who benefits from herd immunity (babies, immunocompromised, elderly).
- Herd immunity threshold calculation (2 marks): Know the formula Threshold = 1 - (1/R₀). Show working. Be able to use it to explain why measles needs higher coverage than flu.
- Ethical discussion (4 marks): Individual choice vs community benefit; risks of vaccine vs risks of disease; protecting vulnerable populations who cannot be vaccinated. Balance arguments — do not just list positives.
Common mark losses: Saying vaccines cause disease (they trigger immune response, not disease). Explaining herd immunity as "everyone is vaccinated" — it means enough people are immune, including naturally immune individuals. Not naming memory cells as the mechanism for long-term protection.