Core Topic 1

1
Core Topic 1
The aims of immunisation national policy and
schedules
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Learning Outcomes

• To be able to explain the aims of immunisation,
  describe national policy and schedules and deal
  with variations to the schedule

3
Learning Objectives

• Explain the different factors that inform vaccine
  policy decisions
• Access current vaccine policy
• Describe the current UK vaccine schedule
• Describe how immunisation programmes are
  monitored through the use of surveillance and the
  COVER programme

4
Public health

• The two public health interventions with the
  greatest impact are clean water and vaccination
• Vaccination is the most effective medical
  intervention in the world

5
History of Vaccination

• Historical recordings of attempts of vaccination
  from 7th century but not really recognised or
  successful until
• 1796 Edward Jenner demonstrated that inoculation
  with cowpox virus produced protection from
  infection with smallpox.
• (Hence Vaccination taken from vacca the
  latin word for cow)
• 1860s-1890s Louis Pasteur produced vaccines
  against chickenpox, cholera, diphtheria, anthrax
  and rabies
• Early 20th Century toxoid vaccines against
  diphtheria and tetanus produced following
  discovery of effective inactivation with
  chemicals
• Post World War 2 successful live viral vaccines
  developed using cell culture techniques
• Present and future new technologies constantly
  developing recombinant protein vaccines, DNA and
  conjugate vaccines

6
Components of vaccination programmes
Vaccine delivery - supply, clinics
Vaccine development
Communication
Surveillance of coverage
Monitoring attitudes to vaccination
Policy development
Surveillance of population susceptibility
Adverse events surveillance
Predicting the future - modelling
Surveillance of diseases
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Development of a vaccination programme

• The aim of a vaccination programme is to control
  a disease successfully
• Before designing a vaccine programme, important
  to establish
• Is there a need for the programme?
• i.e. does the disease cause a significant
  public health problem?
• Is a suitable vaccine available that is safe and
  effective?

8
New vaccines for UK children? Definite or
probable

• Newer vaccines for diseases already targeted in
  the childhood programme
• inactivated polio vaccine (IPV)
• acellular pertussis vaccine (aP) 5 components
• New combinations of existing vaccines
• DTaP/Hib/IPV (Paediacell)
• Men C / Hib

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New vaccines for UK children?Probable or possible

• More widespread use of vaccines already used
  selectively
• hepatitis B
• varicella vaccine
• Vaccines where the need is not yet established
• influenza vaccines for children

10
New vaccines for UK children?Not yet clear

• Vaccines where there is no current UK need
• Meningococcal ACWY conjugate vaccines
• Vaccines where development of effective vaccines
  has been problematic
• Eg. Vaccines against group B meningooccus
• Vaccines where safety concerns have been raised
• Eg. rotavirus

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Establishing the need for a vaccination programme

• Disease incidence
• Age distribution
• Trends
• Disease complications
• Mortality
• These are ascertained by surveillance and also
  through published literature and special studies

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Hepatitis B vaccine policy

• Current policy
• Selective vaccination of high risk groups
• Antenatal screening and vaccination of infants
  born to positive mothers
• Additional policy options
• Universal vaccination of adolescents
• Universal vaccination of children
• Geographically selective policy
• Combination of the above

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Acute HBV laboratory reports to CDSCBy age
group, 1990-2002
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Objectives of surveillance

• Surveillance needs to be carried out both before
  and after a vaccine programme is introduced
• Pre-implementation of vaccine
• To estimate burden of disease
• To decide vaccination strategy
• Post implementation of vaccine
• To monitor effectiveness of vaccine strategy

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Reported acute HBV infections by exposure
category (n675/yr)
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Surveillance for Vaccine Programmes

• Disease incidence
• Reports of disease from a variety of sources are
  collated by the Centre for Infections (CfI)
• Susceptibility
• Residual blood samples used for serological
  surveillance
• Vaccine Coverage
• Vaccine uptake monitored across the country,
  collated by CfI from local Child Health Computers
• Monitoring adverse events and vaccine safety
• Collated by Medicines and Healthcare products
  Regulatory Agency (MHRA) Yellow Card scheme
• Investigated by CfI and immunisation experts
  worldwide

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Pertussis notifications
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Disease incidence

• Main sources of data
• - Statutory notification
• - Laboratory reporting
• Death notification
• Other sources
• - Hospital episodes
• - Sentinel physician reporting
• - Paediatric surveillance

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Serological surveillance

• Residual blood samples from routine tests are
  used to provide information on disease immunity
  in population
• Collected on an annual basis for all age groups
  and sent to HPA seroepidemiology unit
• Anonymous age and sex known only
• Serological surveys provide information on how
  well-protected population is against preventable
  disease this needs to be known when deciding on
  new vaccine programmes or the need for campaigns

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Rubella susceptibility, 1991
25
Males
20
Females
15
susceptible
10
5
0
0
5
10
15
20
25
30
35
40
Age
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Vaccination CoverageCOVER (Cover of Vaccination
Evaluated Rapidly)

• It is important to know what proportion of any
  targeted population has received each vaccine
• Since 1988 computerised child health registers
  across the country have held vaccination details
  for all children resident in the area
• Every 3 months, information collected by CfI from
  each child health computer as to number of
  children who have completed scheduled vaccine
  courses at 1,2 5y of age
• This information used to evaluate and improve
  immunisation coverage by regular feedback to
  local areas

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COVER (cont)

• Additionally, COVER data can be used to
• detect change rapidly and monitor trends in
  uptake
• provide information on impact of media stories
• look for pockets of poor coverage
• estimate vaccine efficacy
• measure impact and success of a vaccination
  campaign
• It is thus vital than anyone who gives an
  immunisation, records and reports that
  immunisation to the childs local Child Health
  Computer

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Issues in vaccine policy decisions

• As well as information about disease incidence,
  vaccine safety and efficacy from surveillance,
  vaccine policy makers need to consider
• Aim of programme
• Cost of programme
• Population accessibility
• Cultural attitudes and practices
• Facilities available for delivery

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Aim of immunisation programme

• Need to decide overall aim
• To protect those at highest risk
• (selective immunisation strategy)
• or
• To eradicate, eliminate or contain disease
• (mass immunisation strategy)

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Selective vaccination

• Vaccine does not need to be given to all, only to
  those at increased risk of disease
• Travel
• e.g. Japanese B encephalitis
• Occupational risk
• e.g. Anthrax
• High risk groups
• e.g. Hepatitis B vaccine for neonates,
• Outbreak control
• e.g. Hepatitis A vaccine

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Mass vaccination

• Either
• EradicationDisease and its causal agent have
  been removed worldwide e.g. smallpox
• Elimination
• Disease has disappeared from one WHO Region but
  remains elsewhere e.g. polio
• Containment
• The point at which the disease no longer
  constitutes a "significant public health problem
  e.g. Hib

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Mathematical modelling and cost effectiveness

• Used to predict impact of a vaccination programme
  and thus inform policy by
• Modelling whether a programme can achieve its
  goals
• Comparing the costs and impact of various
  programme options

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UK mechanisms for making and implementing of
vaccination policy

• Recommendations for vaccine policy
• Joint Committee on Vaccination and Immunisation
• Vaccine policy decisions
• Department of Health
• Licensing of vaccine
• Medicines and Healthcare products Regulatory
  Agency (MHRA)
• Purchase of vaccine
• Dept Health from pharmaceutical companies
• Control of vaccine (including batch release)
• National Institute for Biological Standards and
  Control

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Joint Committee of Vaccination and Immunisation
(JCVI)

• The JCVI is an independent expert advisory
  committee.
• Its role is
• To advise the Secretaries of State for Health,
  Scotland, Wales and Northern Ireland on matters
  relating to communicable diseases, preventable
  and potentially preventable through immunisation
  
• Taken from JCVI websitehttp//www.advisorybodi
  es.doh.gov.uk/jcvi/)
• They review all available evidence and make
  recommendations to the Dept Health
• who then decide on and make UK vaccine policy

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UK Vaccine Policy published in

• Immunisation against Infectious Disease
• (the Green Book)
• Currently available on Dept Health website
• Chapters can be individually downloaded from the
  website and printed off - updated chapters will
  replace previous versions as they become
  available
• Chief Medical Officer Updates, Letters,
  Publications and Urgent Communications
• These detail any changes to vaccine policy and
  recommendations

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Vaccination schedule in UK May 2006

• Primary immunisation
• 2, 3 and 4 months
• Diphtheria-tetanus-acellular pertussis,
• inactivated polio vaccine
• Haemophilus influenzae type b DTaP-Hib-IPV
• Meningococcal group C conjugate MenC
• 12-15 months
• Measles-mumps-rubella MMR

Booster immunisation 3½-5 years Diphtheria-tetanus
-acellular pertussis Inactivated polio
vaccine DTaP-IPV or dTaP/IPV Measles-mumps-rubel
la MMR 15 years Tetanus-low dose
diphtheria Inactivated polio vaccine Td-IPV
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Changes to Childhood Schedule Sept. 2006

• PCV pneumococcal conjugate vaccine (7 valent)
  at 2 and 4 months boost at 13 m with MMR
• Men C at 3 4 months boost at 12 m with Hib
• BCG school programme stopped for targeted
  neonatal immunisation family history and
  country of origin
• MMR 2 doses under age 25y

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Conjugate pneumococcal vaccines

• Streptoccoccus pneumoniae
• 90 plus different serotypes
• carried in upper respiratory tract
• Wide range of disease
• Conjugate vaccines contain between 7 and 11
  serotypes responsible for disease in children
• 80 of childhood pneumococcal disease caused by 7
  serotypes
• Induce long-term memory
• Reduce carriage
• Induce herd immunity

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Place of conjugate pneumococcal vaccine in UK?

• Cost effectiveness data needed to justify routine
  use in UK infants
• Lower rate of invasive disease in UK vs US
• Role of herd immunity and serotype replacement
  may be crucial
• Appropriateness for UK schedule
• 3 doses plus booster?
• Acceptability of 3rd injections
• What combinations (MenC/PCV) or alone?

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Varicella Vaccine

• Live attenuated vaccine licensed July 2002 in UK
• Widely used in Japan and US (with MMR)
• Routine vaccination will have an impact on burden
  from both
• Varicella
• Zoster
• Cost effectiveness analysis and modelling needed

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Chickenpox - epidemiology
Photograph by kind permission of Dr Philip Welsby
and Dr Mike Jones, Edinburgh
Photograph by kind permission of Dr S Ruffle
Twyford
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Annual burden of diseasevaricella zoster
Sources Edmunds et al. Vaccine (2001) Brisson
Edmunds Arch Dis Child (2003)
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Arguments for mass varicella vaccination

• In favour
• Preventable deaths and hospitalisations
• Large economic cost, particularly through
  parental work-loss
• Against
• Increase in average age at infection could lead
  to more severe disease (particularly if low
  coverage)
• Decrease in incidence of varicella could lead to
  an increase in the incidence of zoster due to the
  loss of exogenous boosting

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Effect of varicella vaccination on zoster
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Summary

• Infant varicella vaccination highly unlikely to
  be cost-effective
• Adolescent vaccination may be cost-effective in
  UK
• Adult vaccination against zoster may also be
  cost-effective
• No other economic analysis has looked at effect
  on zoster
• Most have not taken account of herd effects

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New vaccines for UK children?Vaccines where
development is problematic

• Group B meningococcal vaccines
• Concerns about tolerance and safety have limited
  development of conjugates
• Problems of non capsular (group B) meningococcal
  vaccines
• Efficacy in the age group at greatest risk
• Coverage of protection against extremely diverse
  organism
• Feasibility of large enough conducting efficacy
  studies

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Confirmed meningococcal infections1998-2003
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Main approach to meningococcal group B vaccine

• Outer membrane vesicles of epidemic strains
• Moderate efficacy in Norway, Cuba, South America
• Limited duration of protection
• Only useful in older age groups
• How much group B disease will be covered?
• Will there be any heterotypic protection
• Will it cover variants of same Por A
• May be useful in response to an epidemic of a
  single clone
• Currently being conducted in New Zealand

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New vaccines for UK children?Possible

• Influenza is major cause of morbidity and
  mortality in developed world
• Elderly account for the vast majority of deaths
• Hospital admissions common in other age groups
• US have now recognised the need to vaccinate
  children under two
• Current influenza vaccine
• Need for annual vaccination
• Possible role of live attenuated vaccines in the
  future?
• Children are major source of infection for others

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Hospitalisation rates for influenzaUSA studies
/100,000

• Children
• Under one 496-1038
• Aged 1-2 yrs 186
• Aged 3-4 yrs 86
• Aged 5-14 yrs 41
• Adults
• Aged 15-44 yrs 23-25
• Aged 45-64 yrs 13-23
• Aged gt 65 yrs 125-228
• What is the burden of influenza in children in
  the UK?

May already have been reduced by between 30-70
by vaccination
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Live attenuated influenza vaccine

• Live attenuated, cold-adapted viruses
• Replicate in upper but not in lower airways
• Protective mucosal immunity without disease
• Trivalent preparation given by nasal spray
• same strains as killed vaccine (A H3N2, A H1N1,
  B)
• LAIV is an now recommended in the US
• an alternate to inactivated vaccine for healthy
  people aged 5-49 years
• Not for those at high risk, or with asthma

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Recommendations in the US

• Inactivated vaccine is strongly recommended for
• All age groups at risk
• Healthy adults aged over 65 yrs
• Adults aged 50-64 yrs (high prevalence of RFs)
• Inactivated vaccine is encouraged (where
  feasible)
• Healthy children aged 6-23 months
• Moving towards a policy of annual vaccination
  for all aged 6-23 months within three years
• Also recommending use of LAIV for older healthy
  children
• Role of influenza vaccines for the UK unclear

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Summary

• Several likely developments in the UK schedule
• Introduction will depend upon good surveillance
  data and economic and epidemiological analysis
• Practical issues must not be under-estimated
• number of injections
• complexity of schedules
• Safety issues have the ability to side-track
  programme
• Important that justification for the introduction
  of vaccines are clear