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Higher Human 3.7
3.7- Immunisation
Question | Answer |
---|---|
How can immunity be developed by vaccinations? | using antigens from infectious pathogens, so creating memory cells |
What kind of antigens are used in vaccinations? | The antigens used in vaccines can be inactivated pathogen toxins, dead pathogens, parts of pathogens and weakened pathogens. |
What are antigens mixed with when producing vaccines? | an adjuvant |
What does an adjuvant do? | An adjuvant is a substance which makes the vaccine more effective, so enhancing the immune response. |
When does herd immunity occur? | Herd immunity occurs when a large percentage of a population is immunised. |
Why is establishing herd immunity important? | Establishing herd immunity is important in reducing the spread of diseases |
How does herd immunity effect non-immune individuals? | Non-immune individuals are protected as there is a lower probability they will come into contact with infected individuals |
What is the herd immunity threshold? | the percentage of the population that has to be immune for her immunity to be established. |
What can effect the herd immunity threshold? | The herd immunity threshold depends on the type of disease, the effectiveness of the vaccine and the density of the population. |
What is used to establish herd immunity? | Mass vaccination programmes |
Why might difficulties arise in mass vaccination programmes? | Difficulties can arise when widespread vaccination is not possible due to poverty in the developing world, or when vaccines are rejected by a percentage of the population in the developed world |
What is it called when pathogens change their antigens? | Antigenic variation |
Why does antigenic variation cause issue when establishing herd immunity? | This means that memory cells are not effective against them. |
What is an example of a pathogen that regularly undergoes antigenic variation and how is this overcome? | Antigenic variation occurs in the influenza virus explaining why it remains a major public health problem and why individuals who are at risk require to be vaccinated every year. |