Immunisation. 1796 If you understand basic immunology you can explain... How vaccines work and why...
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Transcript of Immunisation. 1796 If you understand basic immunology you can explain... How vaccines work and why...
Immunisation
1796
If you understand basic immunology you can explain...
• How vaccines work and why vaccine failures occur
• Adverse events and their timing• Why the schedule is as it is• Why vaccines cannot overload the
immune system
Physical barriers
• Skin – 2 m²• Mucosal membranes – digestive,
respiratory, reproductive tract – 400 m²
Innate immunity
• Phagocytosis • Macrophage - WBC• Rapid action 0-4 hours• Non-specific – same response each
time• No memory – same response at each
encounter• May destruct the antigen
Adaptive immunity
• Second level of defence• Effectiveness increases with each
encounter• Specific immune response
Types of (adaptive) immunity
•Active Immunity
•Passive Immunity
Passive Immunity
• Transfer of maternal
antibodies
• Administration of antibodies
Active Immunity
• Antibodies produced in response to an infection
• Antibodies produced in response to a vaccination
Types of antibody
• IgG – the only type that crosses the placenta (after 32 weeks)
• IgA – in breast milk – gives some mucosal protection
• IgE – over production associated with anaphylaxis
• Also IgM – maybe further reading!
Active versus passive immunity
• ACTIVE
• Long lasting
• Takes time to be effective
• PASSIVE
• Only short term
• Immediate protection
• http://www.nhs.uk/Video/Pages/Vaccinationanimation2.aspx
Vaccination schedule 2014Age Diseases protected against
2 months Diphtheria, tetanus, whooping cough, polio, Hib, pneumococcal disease Rotavirus
3 months Diphtheria, tetanus, whooping cough, polio, Hib, meningococcal disease type C and Rotavirus
4 months Diphtheria, tetanus, whooping cough, polio, Hib, pneumococcal &
12-13 months
Hib/meningococcal disease type Cpneumococcal diseaseMeasles, mumps & rubella (MMR)
3yrs 4m Diphtheria, tetanus, whooping cough, polioMMR (pre-school immunisations)
12-13yrs HPV (cervical cancer) girls only x doses over 6 month period
13-18yrs Diphtheria, tetanus, polio (school leavers immunisations)
16Meningococcal type C booster from Sept 2013 (13-15 yrs)
Vaccine overload?
Part of body Bacteria
Scalp 1,000,000/cm2
Surface of skin 1000/cm2
Saliva 100,000,000/g
Nasal mucus 10,000,000/g
Faeces Over 100,000,000/g
Contraindications
• Immunosuppression & treatment• Some steroid use• Unstable neurological condition• Previous anaphylactic reaction• Care with live vaccines
• Pyrexia• Acute illness
• Side effects??
Vaccine trials
• Pre-clinical laboratory based work• Phase I – (small scale – adults)• Phase II – (population specific)• Phase III – (100s-1000s participants)• Phase IV vaccines – MHRA reporting
Getting to the schedule
• Research and development• JCVI• Recommendations to DH• Cost and feasibility studies• Supply and delivery• Awareness and training issues
References/further reading
• Immunisation against infectious disease (Green Book) [online] https://www.gov.uk/government/organisations/public-health-england/series/immunisation-against-infectious-disease-the-green-book
• Health Protection Agency website http://www.hpa.org.uk/HPAwebHome