Immunisation

Question 1

How effective are vaccinations?

Answer 1

Vaccination is considered to be the single most effective medical intervention so far, second only to access to clean water as a public health intervention

Question 2

What are the benefits of immunisation?

Answer 2

• Protects individuals and communities from serious infections
• proactive measure for well people
• reflects NHS and professional quality

Question 3

What is meant by the ‘strategic aim’ of the vaccination goal?

Answer 3

selective protection of the vulnerable

elimination through herd immunity and eradication of diseases

Question 4

What is meant by the ‘programmatic aim’ of vaccination?

Answer 4

To reduce mortality and morbidity from vaccine preventable infections

• prevent deaths
• prevent infection
• prevent transmission
• prevent clinical cases
• prevent cases in a certain age group

Question 5

Why are people immunised?

Answer 5

• To prevent individual disease for an entire lifetime
• to halt carriage and transmission (herd immunity is a side effect)
• to eliminate and eradicate disease

Question 6

What are the non-specific defences against pathogens?

Answer 6

• Unbroken skin
• mucous membranes of the gut and lung
• acid and enzymes in the gut
• non-specific metabolism / inactivation

Question 7

What molecules are involved in innate immunity?

Answer 7

Complement, white blood cells and cytokines

Question 8

What are the 3 brief stages that the immune system is involved with?

Answer 8

1. Immunoglobulin is initially not specific
2. Learns specific IgG response
3. Lays down immune memory

Question 9

What is a natural example of passive immunity?

Answer 9

Transfer of antibodies from mother to unborn baby

“maternal antibodies” can protect the baby for up to a year against illness to which the mother is immune

Question 10

What is an artificial form of passive immunity?

Answer 10

Immunoglobulin, which contains antibodies pooled together from the blood of many donors, can be injected into a person who needs antibodies

this is effective passive immunity, but usually disappears within several weeks or months

most types of transfused blood contain antibodies

Question 11

What is meant by active immunity?

Answer 11

Active immunity is usually long-lasting immunity produced by the immune system in response to antigens

the antigens can come from natural infection or from vaccination

the immune system makes antibodies to help destroy antigens

Question 12

What are the benefits of vaccination providing active immunity?

Answer 12

Active immunity occurs without disease or disease complications

Question 13

What is meant by the term “immunological memory”?

Answer 13

The persistence of protection against disease antigens for many years after natural infection or vaccination

Question 14

What is the definition of an antigen?

Answer 14

An antigen is defined as “anything that can be bound by an antibody”

Question 15

What is meant by an “antigenic determinant” or “epitope”?

Answer 15

Antibodies interact specifically with relatively small parts of molecules (antigens)

these are known as antigenic determinants or epitopes

Question 16

What are the different types of antibody?

Answer 16

An antibody is produced to one specific antigen

IgM, IgG, IgA, IgE

Question 17

What is the difference between the primary and secondary immune response?

Which antibodies are involved in these responses?

Answer 17

Primary immune response:

• develops in the weeks following first exposure to an antigen
• mainly IgM antibody

Secondary immune response:

• faster and more power
• mainly IgG antibody

Question 18

Where are antibodies produced from?

Where does the antigen bind to the antibody and what does this lead to?

Answer 18

Antibodies are produced from B lymphocytes

The antigen binds non-specifically to the variable region of the antibody (Ig)

This triggers clonal expansion

There is a 1st wave of IgM production, followed by IgG production

Question 19

What happens after the wave of IgM production, followed by IgG production?

Answer 19

IgG binds tightly to the antigen

through simultaneous complement-binding, IgG facilitates the destruction of the antigen-bearing micro-organism

Question 20

What happens to the levels of IgG after infection resolves?

Answer 20

Levels of IgG decline

One set of the IgG producing B lymphocytes persist with the ability to recognise that specific antigen

This is the immunological memory

Question 21

What is the main difference between active and passive immunity?

Answer 21

active immunity:

• Occurs in natural infection
• involves inactivated or attenuated live organisms

passive immunity:

• involves vertical transmission of autoantibodies from mother to foetus and breastfeeding
• injection of human immunoglobulin

Question 22

What types of organisms is active immunity produced against?

How is this acheived?

Answer 22

Live organisms:

• MMR
• BCG
• yellow fever
• varicella

Inactivated organisms:

• pertussis
• typhoid
• IPV

components of organisms:

• influenza
• pneumococcus

Inactivated toxins:

• diphtheria
• tetanus

Question 23

What are examples of passive immunisation>

Answer 23

HNIG - pooled plasma

Specific - tetanus, botulism, hepatitis B, rabies, varicella

Question 24

What are the advantages of live vaccines?

Answer 24

• A single dose is often sufficient to induce long-lasting immunity
• a strong immune response is evoked
• local and systemic immunity is produced

Question 25

What are the disadvantages of live vaccines?

Answer 25

* Potential to revert to virulence * contraindicated in immunosuppressed patients * interference by viruses or vaccines and passive antibody * poor stability * potential for contamination

Question 26

What are the advantages of inactivated/killed vaccines?

Answer 26

1. Stable 2. constituents clearly defined 3. unable to cause infection

Question 27

What are the disadvantages of inactivated / killed vaccines?

Answer 27

* Need several doses * local reactions are common * adjuvant is needed to keep the vaccine at the injection site and activate antigen presenting cells * shorter lasting immunity