Immunisation Principles And Overview Flashcards
What is a vaccine?
The process that introduces a weakened or dead pathogen with the intent of conferring immunity.
A pool of B and T memory cells made, which can produce a specific and fast response if antigen encountered again.
What is active immunity?
Protection produced by the individuals own immune system
Acquired by natural disease or vaccination
Usually long lasting
What is passive immunity?
Protection provided by transfer of antibodies from immune individuals
Protection temporary - weeks/months
E.g at birth baby has same range of IgG as mother - maternal antibodies breakdown over first few months
Or giving immunoglobulin for short term, immediate disease protection if patient at high risk (neonate, immunocompromised, pregnant)
Why does the vaccine schedule start at 2 months and not before this?
Baby has passive immunity from mother - this may block the vaccine antigen before it can stimulate the infants immune system
How many vaccines are included in the UK routine immunisation schedule?
15 vaccines
What are the 2 types of vaccine?
Live attenuated and inactive
Describe live attenuated vaccines
Made from the disease causing organism that has been weakened to reduce virulence
Provides long lasting immunity
Contains whole bacteria or viruses
Produces immune response but not the disease
What are the disadvantages of live attenuated vaccines?
Potential to revert to disease causing strain (rare)
Can lose potency
Do not work if recipient recently received blood product containing antibodies
Contraindicated in immunocompromised and pregnancy (cannot produce antibody response quick enough to prevent replication)
What examples of live attenuated vaccines are there?
UK schedule:
Rotavirus
MMR
Live attenuated influenza
Others:
Shingles
Chickenpox
BCG
What types of inactivated vaccines are there?
Whole killed Subunit vaccines (acellular): - toxoid - conjugate - recombinant
Describe whole killed vaccines
These contain whole, intact killed organisms
What whole killed vaccines are there?
UK schedule:
Polio (IPV)
Others:
Some inactivated flu
Hepatitis A
Describe subunit vaccines
Do not contain whole bacteria or virus
Contain polysaccharides (sugars) or proteins from the bacteria/virus surface
These parts are enough to trigger immune response
What are toxoid inactivated vaccines?
Based on the toxin produced by the bacteria (not the bacteria itself) - an inactivated version
‘Toxoid’ because they look like toxins but are not poisonous
Adsorbed to aluminium /calcium
What examples of toxoid vaccines are there?
UK schedule:
Diphtheria
Tetanus
Pertussis
Describe conjugate vaccines
Polysaccharide vaccines provide poor immunity in infants
Activity enhanced by conjugation to diphtheria or tetanus toxoid (these are known to create a strong immune response - the immune system recognised them easily and this helps create stronger response to the polysaccharide)
What examples of conjugate vaccines are there?
UK schedule: H influenza Meningitis C Meningitis ACWY Pneumococcus (PVC)
What are recombinant vaccines?
Bacteria/yeast cells used to manufacture vaccine
Small piece of bacteria/virus DNA inserted into the cell to make them produce large quantities of the active ingredient for the vaccine - usually a single protein or sugar)
What examples or recombinant vaccines are there?
UK schedule:
HepB
HPV
Meningitis B
What type of vaccines are the travel vaccines for yellow fever and oral typhoid?
Live attenuated
What type of vaccines are the travel vaccines for rabies and Japanese encephalitis?
Whole killed
When can vaccines be delayed?
Acutely unwell e.g febrile illness
What are some general contraindications to immunisation?
Confirmed anaphylactic reaction to previous dose of vaccine containing same antigens
Confirmed anaphylactic reaction to another component contained in the relevant vaccine e.g egg protein
What is a vaccine adjuvant and why is it added to a vaccine?
Adjuvant = added ingredient to a vaccine
Helps create a stronger immune response to vaccine
Example = aluminium salts
Can cause more local reactions - redness, pain, swelling to injection site and more systemic reactions - fever, chills, body aches
What residuals can be found in vaccines in minute quantities?
Antibiotics (to prevent bacterial contamination during manufacturing) e.g neomycin, streptomycin
Egg proteins - some vaccines grown in chick embryo cells e.g influenza, yellow fever
Yeast proteins
Inactive ingredients e.g formaldehyde
