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Unit 4 Immunology and
Public Health
Unit 4 – Immunology and Public
Health
1. The Immune
System
a)Non-specific
defences
b)Specific cellular
defences
2. Infectious
Diseases and
immunity
a)Transmission and
control
b)Active
Immunisation and
Vaccination and
the evasion of
immune responses
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
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
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
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)
DEAD – the pathogen is destroyed and cannot replicate
itself
antigen
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
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
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.
How
vaccines
work
(simplified)
How
vaccines
work
(includes B
and T cells)
But what was the
first vaccination?
The Smallpox Story video
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
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