Principls of Immunisation Flashcards
what are the 3 aims of immunisation?
prevent onset of disease (primary prevention)
interrupt transmission
Alter course of infection/disease to prevent or limit consequences (secondary prevention)
which type of disease does immunisation control?
communicable diseases
what do vaccines do?
teach the immune system to recognise bacteria and viruses before the individual encounters them as potential pathogens so allowing the body to fight against the pathogen
name 3 immunological mechanisms
active immunity
passive immunity
herd immunity
what are antigens usually made of?
proteins or polysaccharides (sugars)
what are antibodies made of?
proteins
very specific to individual antigens
how are B cells produced?
humoral immune system
- mature in the bone marrow
- triggered to produce antibody when they encounter foreign antigen
how are T cells produced?
cell-mediated immune system
- mature in Thymus
- CD4 and CD8 cells
- orchestrate response of immune system by binding to other cells and sending out signals
what is passive immunity?
transfer of pre-formed antibodies (immunoglobulins)
through what 2 methods can passive immunity be acquired?
mother to unborn baby via placenta - lasts up to 1 year - doesn't protect against all antigens from another person or animal - antibodies from blood donors - human normal Ig - specific Ig
what 2 components of the immune system are present in passive immunity and what do they protect against>
human immunoglobulin
- hep B, rabies, varicella zoster etc
anti-toxin
- diphtheria, botulinum etc
what are the advantages of passive immunity?
rapid action post-exposure can attenuate illness outbreak control can be used if live vaccine is contraindicated
what are the disadvantages of passive immunity?
short term protection short time window blood derived hypersensitivity reactions expensive
natural vs artificial passive immunity?
natural = transplacental transfer artificial = human IgG
natural vs artificial active immunity?
natural = natural infection artificial = artificial immunisation
mechanism of vaccines?
induce cell mediated immunity responses and serum antibodies
different vaccines induce different speed and sustainability of response
what are live vaccines?
attenuated organism, replicates in host
- OPV
- MMR
- varicella
- rotavirus
- flu
what are inactivated vaccines?
suspensions of killed organism
- pertussis (whooping cough)
- typhoid
OR
subunit vaccines
- toxoids (e.g diphtheria, tetanus, pertussis)
- polysaccharides (e.g pneumococcal, typhoid)
OR
conjugate vaccines
- polysaccharide attached to immunogenic proteins
- Hib, MenC
what are 5 contraindications to vaccines?
confirmed anaphylaxis to previous dose of same vaccine
immunosuppression or pregnancy (if live vaccine)
egg allergy
severe latex allergy
acute or evolving illness (wait until resolved)
what is herd immunity?
unvaccinated individuals are protected through having sufficiently large population of population vaccinated
what is the proportion of the population required to be immune based on?
transmissibility and infectiousness of organism
social mixing in population
give 3 examples of herd immunity?
measles = 90%
umps = 75-86%
smallpox = 80-85%
requires that there is no reservoir of infection
what is the Scottish immunisation programme?
programme of vaccination
what is the purpose of the vaccine schedule in the UK?
to provide early protection against infections that are most dangerous for the very young (whooping cough, meningococcal, pneumococcal)
to ensure continued protection by providing subsequent immunisations and booster doses before reaching age when risk increases
how is the age at which vaccine is offered based on?
risk of disease
level of protection
risk of complications
are vaccines still given, even if older than recommended age?
yes
if a course of immunisation is interrupted, does it need to be restarted?
no
can usually be resumed and completed due to immunological memory
name 11 routine childhood vaccines
hexavalent meningococcal group B rotavirus pneumococcal Hib/meningococcal group C MMR influenza diphtheria, tetanus, pertussis and polio tetanus, diphtheria and polio booster meningococcal groups A, C, W and Y HPV
what selective childhood vaccines are given for at risk children?
flu
pneumococcal polysaccharide vaccine
BCG
Hep B
name 4 adult programmes of vaccination
pneumococcal polysaccharide vaccine
shingles (70 y/o)
seasonal flu
various selective programmes
when and how must public health be notified of a disease?
clinical suspicion of specific disease or health risk state
- notification in writing within 3 days
- notification by phone ASAP if urgent
what characterises diphtheria?
URTI
sore throat
low grade fever
white adherent membrane on tonsils, pharynx and/or nasal cavity
what causes diphtheria?
aerobic gram-positive bacterium
corynebacterium diptheriae
what causes meningococcal disease?
invasive infection due to Neisseria meningitidis
how serious is meningococcal disease?
10-20% mortality in children
which types of meningococcal disease can be vaccinated against>
groups:
- A
- C
- W
- Y135
- B
how does meningococcal disease spread?
person-person contact through respiratory droplets
incubation = 3-5 days
colonisation of nasopharynx
what are the 3 phases of vaccine trials?
phase 1 = is it safe, is it immunogenic
phase 2 = how reactogenic is it, what dose, how does it compare with current vaccines
phase 3 = is it efficacious, are there any rarer reactions/safety issues?
