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

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!