Immunisation Flashcards
How effective are vaccinations?
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
What are the benefits of immunisation?
- Protects individuals and communities from serious infections
- proactive measure for well people
- reflects NHS and professional quality
What is meant by the ‘strategic aim’ of the vaccination goal?
selective protection of the vulnerable
elimination through herd immunity and eradication of diseases
What is meant by the ‘programmatic aim’ of vaccination?
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
Why are people immunised?
- To prevent individual disease for an entire lifetime
- to halt carriage and transmission (herd immunity is a side effect)
- to eliminate and eradicate disease
What are the non-specific defences against pathogens?
- Unbroken skin
- mucous membranes of the gut and lung
- acid and enzymes in the gut
- non-specific metabolism / inactivation
What molecules are involved in innate immunity?
Complement, white blood cells and cytokines
What are the 3 brief stages that the immune system is involved with?
- Immunoglobulin is initially not specific
- Learns specific IgG response
- Lays down immune memory
What is a natural example of passive immunity?
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
What is an artificial form of passive immunity?
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
What is meant by active immunity?
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
What are the benefits of vaccination providing active immunity?
Active immunity occurs without disease or disease complications
What is meant by the term “immunological memory”?
The persistence of protection against disease antigens for many years after natural infection or vaccination
What is the definition of an antigen?
An antigen is defined as “anything that can be bound by an antibody”
What is meant by an “antigenic determinant” or “epitope”?
Antibodies interact specifically with relatively small parts of molecules (antigens)
these are known as antigenic determinants or epitopes
What are the different types of antibody?
An antibody is produced to one specific antigen
IgM, IgG, IgA, IgE
What is the difference between the primary and secondary immune response?
Which antibodies are involved in these responses?
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
Where are antibodies produced from?
Where does the antigen bind to the antibody and what does this lead to?
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
What happens after the wave of IgM production, followed by IgG production?
IgG binds tightly to the antigen
through simultaneous complement-binding, IgG facilitates the destruction of the antigen-bearing micro-organism
What happens to the levels of IgG after infection resolves?
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
What is the main difference between active and passive immunity?
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
What types of organisms is active immunity produced against?
How is this acheived?
Live organisms:
- MMR
- BCG
- yellow fever
- varicella
Inactivated organisms:
- pertussis
- typhoid
- IPV
components of organisms:
- influenza
- pneumococcus
Inactivated toxins:
- diphtheria
- tetanus
What are examples of passive immunisation>
HNIG - pooled plasma
Specific - tetanus, botulism, hepatitis B, rabies, varicella
What are the advantages of live vaccines?
- A single dose is often sufficient to induce long-lasting immunity
- a strong immune response is evoked
- local and systemic immunity is produced
What are the disadvantages of live vaccines?
- Potential to revert to virulence
- contraindicated in immunosuppressed patients
- interference by viruses or vaccines and passive antibody
- poor stability
- potential for contamination
What are the advantages of inactivated/killed vaccines?
- Stable
- constituents clearly defined
- unable to cause infection
What are the disadvantages of inactivated / killed vaccines?
- 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
