UNIT 3 - KA7
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How can immunity be developed
Immunity can be developed by vaccination using antigens from infectious pathogens so creating memory cells
What is a vaccination
A vaccination is a medical treatment used to introduce antigens to the human body to trigger an immune response
Which forms of antigens can be in vaccines
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 a vaccine
Antigens are usually mixed with an adjuvant when producing the vaccine
What is an adjuvant
An adjuvant is a substance which makes the vaccine more effective, so enhancing the immune system
When does herd immunity occur
Herd immunity occurs when a large percentage of the population is immunised
What is the effect of establishing herd immunity
Establishing herd immunity is important in reducing the spread of diseases
What does the herd immunity threshold depend on
The herd immunity threshold depends on the type of disease, the effectiveness of the vaccine and the density of the population
Which programmes are designed to establish herd immunity to a disease
Mass vaccination programmes are designed to establish herd immunity to a disease
When do difficulties arise in a developing country in establishing herd immunity
Difficulties can arise when widespread vaccination is not possible due to poverty in the developing world
When do difficulties arise in a developed country in establishing herd immunity
Or when vaccines are rejected by a percentage of the population in the developed world
Define the term antigenic variation
Some pathogens change their antigens.
Why are some memory cells ineffective
Some pathogens can change their antigens. This means that the memory cells are not effective against them
Explain why a new influenza vaccine is needed each year
New strains of the influenza virus arise each year showing antigenic variation. This is why a new vaccine has to be given each year to vulnerable individuals
Influenza virus
Antigenic variation occurs in the influenza virus explaining why it remains a major public health problem and why individuals who are at risk required to be vaccinated every year
How are non immune individuals protected
Non immune individuals are protected as there is a lower probability they will come into contact with infected individuals