U3 KA7 - Immunisation

Question 1

Define Immunisation

Answer 1

Immunisation is the process by which a person develops immunity to a disease-causing organism

Question 2

What is active immunity?

Answer 2

The phrase active immunity refers to the protection gained as a result of the person’s body producing its own antibodies ​

Question 3

What is Natural Immunity?

Answer 3

Natural immunity occurs when a person has previously been infected by a pathogen and becomes immune due to a primary immune response

Later exposure to the same pathogen will result in a secondary response to prevent the pathogen infected the individual again.

Question 4

What is the role of a Vaccine

Answer 4

Vaccines can contain inactivated pathogen toxins, dead pathogens, parts of pathogens or weakened pathogens and therefore stimulates a primary response against the antigen therefore initiating the immune response without causing symptoms of the disease

Question 5

Describe the method of Vaccination

Answer 5

1. An introduced antigen is mixed with a chemical known as an adjuvant
2. The presence of the antigen induces Lymphocyte B & T cells production. These cells form specific antibodies to combat the antigen introduced. (Primary response)
3. Phagocytes then can engulf and destroy pathogens removing them from the body
4. B and T cells will persist in the body as memory cells and will subsequently initiate a secondary response if the individual is exposed to the pathogen at a later date
5. The individual will not become ill as they have acquired active immunity

Question 6

What is an Adjuvant

Answer 6

A substance which promotes antigen activity and enhances the immune response)​

Question 7

What is Herd Immunity?

Answer 7

Herd immunity is a form of indirect protection from infectious disease that occurs when a large percentage of a community is immune to the infection

Question 8

What is the Purpose of Herd Immunity?

Answer 8

It acts to protect individuals who are not immune and also those who are not eligible for certain vaccines (e.g. infants, pregnant women, or immunocompromised individuals) to slow/stop the spread of disease

Question 9

How does Herd Immunity Work?

Answer 9

When a critical proportion of a population has immunity against a infectious disease (natural or artificial), most members of that community are protected against that disease and do not pass the infection on to others therefore there is less opportunity for an outbreak due to a lower chance of contact with infection

Question 10

What are some of the factors that decide the herd immunity threshold?

Answer 10

• The disease’s mode of transmission (airborne, faecal-oral route)​
• The effectiveness of the vaccine​
• Infectiousness of the disease ​
• Population density (the greater population density, the greater ability to spread)

Question 11

Describe the limitations to Herd Immunity

Answer 11

• Uptake of vaccination/no vaccination
  If the number of people vaccinated against a specific disease drops in a population, it leaves the rest of the population at risk of mass infection, as they are more likely to come across people who are infected and contagious.
• Type of disease
  Herd immunity only works for diseases that are spread directly between people. It is impossible for non contagious diseases e.g. tetanus​
• Quality of vaccine
  Herd immunity can also be affected by the quality and effectiveness of the vaccine being used.

Question 12

What is a immunisation program

Answer 12

a policy in public health medicine to establish herd immunity to a number of diseases. ​

Some people in the community may be not eligible for certain vaccines (cancer treatments or immunosuppressant), therefore non immune people can be protected by the majority of immunised people.​

Question 13

Whats a problem with immunisation programs?

Answer 13

1. When widespread vaccination is not possible due to malnutrition and poverty (the developing world)
2. When large numbers of the population reject immunisation programmes (developed world).

Question 14

What is Antigenic variation?

Answer 14

A change in surface antigens on an infectious organism to help the pathogen evade the immune systems of potential hosts. ​

This evolutionary trick allows them to continue growing and spreading in populations, maintaining their existence.

Question 15

What is the result of Antigenic Variation?

Answer 15

This means the antibodies produced by memory cells that we have acquired through natural or artificial immunity will no longer work​ and new specific antibody will need to be made to combat an evolved pathogen.

Some organisms are more successful than other; they change so much that people must design a new vaccine every year. (e.g. the Influenza)