1. Unit 4 - Immunology and Public Health

2. Unit 4 – Immunology and Public Health
1. The Immune System
2. Infectious Diseases and immunity
Non-specific defences
Specific cellular defences
Transmission and control
Active Immunisation and Vaccination and the evasion of immune responses

3. By the end of this section you will be able to …..
2. Infectious Diseases & immunity
b) Active immunisation, vaccination and evasion
By the end of this section you will be able to …..
State how active immunity can be achieved
describe what a vaccine is
describe the effect of a vaccine on the immune system immediately after vaccination
describe the effect of a vaccine on the immune system when the body comes into contact with the same pathogen in later life
Give examples of antigens used in vaccines

4. Active Immunity
Immunisation is the process by which a person develops immunity to a pathogen
Active Immunity is when the protection is gained as a result of a person producing antibodies
There are 2 types of active immunity:
Naturally acquired active immunity:
a person who survives an infection by pathogens has naturally acquired immunity (by making antibodies and memory cells)
Artificially Acquired Active Immunity
achieved by vaccination

5. What is a Vaccine?
Active immunity can be developed by receiving a vaccination.
A vaccine is designed to illicit an immune response without producing the full blown infection.
The vaccine is prepared with antigens from infectious pathogens

6. Vaccines There are 4 main types of vaccines which may contain:
inactivated pathogen toxins
dead pathogens,
parts of pathogens (sub-unit) or
weakened pathogens (attenuated)

7. DEAD – the pathogen is destroyed and cannot replicate itself e. g
DEAD – the pathogen is destroyed and cannot replicate itself e.g. polio WEAKENED – the pathogen has been altered so it cannot cause the disease e.g. measles PART OF PATHOGEN – only the protein coat of the pathogen is used e.g. Hepatitis B INACTIVATED TOXIN – the toxins produced by the pathogen are injected e.g. tetanus
antigen

8. Examples of antigens found in vaccines
Form of antigen in vaccine
Examples of disease to which active immunity is acquired
Dead pathogens (the pathogen is destroyed and cannot replicate itself)
Hepatitis A and polio
Weakened pathogens (the pathogen has been altered so it cannot cause the disease)
Rubella, mumps and measles
Parts of pathogens (only the protein coat of the pathogen is used)
Hepatitis B and HPV
Inactivated toxin (the toxins produced by the pathogen are injected)
Diphtheria and Tetanus

9. Adjuvants Antigens used in vaccines can also be mixed with an ADJUVANT
This is a chemical that enhances the immune response
Adjuvants promote the activity of the antigen in order to:
To induce B cells to produce antibodies and cause the primary immune response.
To produce memory cells so that they remain to give a faster secondary immune response if we ever come across the pathogen again.

10. This is how vaccines protect you against dangerous infectious diseases

13. How vaccines work (simplified) How vaccines work (includes B and T cells)

14. But what was the first vaccination?

15. The Smallpox Story video
Watch the video (title)

16. Mass vaccination
Edward Jenner was the first person to develop a vaccine.
He noticed that people who had contracted cowpox were more likely to survive the deadly smallpox virus.
He injected someone with cowpox and then exposed them to smallpox.
This was the first ever vaccine and is named after the latin word for cow – vacca
Through the use of vaccinations, smallpox is now eradicated around the world.
We hope to eradicate more diseases using vaccination programmes.
Complete the Edward Jenner Exercise. Read the exercise and answer the questions
You can talk through this and do the reading exercise

17. Can you now …. State how active immunity can be achieved
describe what a vaccine is
describe the effect of a vaccine on the immune system immediately after vaccination
describe the effect of a vaccine on the immune system when the body comes into contact with the same pathogen in later life
Give examples of antigens used in vaccines