Community Q&A
A-Level Biology October/November 2024 Q5(b): Polio is a highly infectious viral disease. The virus infects the nervous system of hum…
A-Level Biology · Paper 9700/23 · October/November 2024 · Question 5(b) · [4 marks]
Polio is a highly infectious viral disease. The virus infects the nervous system of humans. The disease can cause total paralysis within hours and can be fatal. The Global Polio Eradication Initiative (GPEI) was started in 1988 by the World Health Organization. In 2022, polio had been successfully eradicated from most of the world. However, cases of the disease have been recorded in some countries. Discuss the steps that must be taken by health authorities during a vaccination programme if an infectious disease, such as polio, is to be eradicated from the whole world.
A full-marks model answer with a mark-by-mark examiner breakdown is below.
1 answer
- accepted ✓
For a global eradication programme to be successful, several key steps must be taken by health authorities.
Firstly, a very high proportion of the world's population must be vaccinated to establish herd immunity. This significantly reduces the number of susceptible individuals, breaking the chain of transmission and protecting those who cannot be vaccinated.
Secondly, the vaccine must be made available to the entire global population, including people in remote and rural areas, not just urban centres. This ensures that there are no pockets of the population where the virus can continue to circulate.
Thirdly, continuous surveillance is required to actively search for new cases of the disease. When a case is identified, contact tracing must be implemented immediately to find and vaccinate all individuals who may have been exposed, preventing further spread.
Finally, a public education campaign is crucial. This should inform people about the benefits and safety of the vaccine to encourage high uptake, and to counter misinformation that could lead to vaccine hesitancy.
How the marks are awarded
- B1 — The model answer correctly refers to the need to vaccinate a high proportion of the population to achieve herd immunity, which is a direct match for mark point 3.
- B1 — The answer states that the vaccine must be made available globally, including to rural populations, which earns mark point 2.
- B1 — Credit is given for mentioning the need for surveillance and contact tracing to find and manage new cases, as described in mark point 7.
- B1 — The final point discusses the importance of an education campaign to inform the public and counter misinformation, fulfilling the criteria for mark point 9.
Common mistakes
- Simply stating 'vaccinate everyone' without referring to the concept of herd immunity or the need to reach a 'high proportion' of the population.
- Focusing on the treatment of infected individuals (e.g., giving them medicine) rather than the preventative steps of a vaccination programme aimed at eradication.
- Describing how a vaccine works at the cellular level (e.g., production of memory cells) instead of answering the question about the public health steps of a vaccination programme.
- Giving answers that are too generic, such as 'have enough money' or 'good transport', without linking them specifically to the programme, for example 'provide funding for vaccine production and distribution' or 'maintain a cold chain during transport'.
Examiner tip: For 'discuss' questions about large-scale biological programmes, think beyond the core science and consider the logistical, financial, and social factors required for successful implementation.
AI-generated model answer, grounded in the official Cambridge mark scheme and reviewed by the MarkScheme team. Mark your own answer to this question →
Your answer
Sign in to answer this question.