Immunisation. 1796 If you understand basic immunology you can explain... How vaccines work and why vaccine failures occur Adverse events and their timing.

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

Vaccination is based on specificity & memory

Vaccination schedule 2012Age Diseases protected against

2 months Diphtheria, tetanus, whooping cough, polio, Hib, pneumococcal disease

3 months Diphtheria, tetanus, whooping cough, polio, Hib, meningococcal disease type C

4 months Diphtheria, tetanus, whooping cough, polio, Hib, pneumococcal & meningococcal disease type C

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

13-18yrs Diphtheria, tetanus, polio (school leavers immunisations)

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] http://immunisation.dh.gov.uk/category/the-green-book/

• Health Protection Agency website http://www.hpa.org.uk/HPAwebHome

Thank you!