The design, evaluation, and management of immunisation programmes

The design, evaluation, and management of Immunisation programmes

This section covers:

• The design, evaluation, and management of Immunisation programmes
• Choices in developing an immunisation strategy

Immunisation

Aim of immunisation: to provoke immunological memory to protect individual against a particular disease.

Two types of immunisation:

• Passive: Immediate protection with temporary source of antibody, e.g. Immunoglobulin (Ig's) and antitoxins
• Active: longer term protection leading to the formation of antibodies

Types of vaccines

Live vaccine (attenuated strains which replicate in host)

Live vaccines include:  Measles Mumps Rubella (MMR), oral  polio, Bacille Camette Guerin (BCG), Yellow Fever, Live attenuated Influenza (LAIV) and Herpes Zoster vaccine.

• Single dose often sufficient to induce long-lasting immunity
• Act like natural infection
• Long duration of immunity
• Less stable: may revert to a virulent strain
• Can cause disease in immuno-suppressed, (exception is HIV patients where do recommend, apart from BCG)

Inactivated vaccine (suspensions of whole intact killed organisms OR components of organism important in protection)

Inactivated vaccines include:  Diphtheria Tetanus Pertussis (DTP), typhoid, Hepatitis B, flu, rabies, meningitis (ACWY, B) Hib, HPV

• Stable
• Unable to cause the infection
• Need multiple doses and booster
• Shorter lasting immunity

Contra indications to immunisation

• Very few real contra-indicators - a confirmed anaphylactic reaction to a previous dose of the vaccine or to a component of the vaccine
• Immuno-suppression (no live vaccines)

Vaccine failure

• Primary: individual fails to make adequate immune response to initial vaccination
• Secondary: individual makes initial adequate response, but then immunity wanes over time

Vaccination programmes

Development of a Vaccine Programme

Prior to designing a vaccine programme, must establish:

• Is there a need for the programme? - does the disease cause a significant public health problem?
• Is a suitable vaccine available that is safe and effective?

Aim of Immunisation Programme

• To protect those at highest risk (selective immunisation strategy)

OR

• To eradicate, eliminate or contain disease (mass immunisation strategy)

Vaccination strategies

A. Selective Vaccination

• Given to those at increased risk
• Examples - for travel, e.g. Japanese B encephalitis, Typhoid, Hepatitis A; occupational, e.g. Hepatitis B, Anthrax, Varicella, MMR; At-risk groups                  
• E.g. Hepatitis B vaccine for neonates born to Hepatitis B positive mothers, Pertussis vaccine for pregnant women to protect their infants from birth; chronic disease, e.g. Splenectomy - meningococcal, Hib, Pneumococcal; outbreak, e.g. Hepatitis A.

B. Mass Vaccination

Either

• Eradication - Disease and its causal agent have been removed worldwide, e.g. small pox
• 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

Issues in Vaccine Policy Decisions

• Aim of programme
• Cost of programme
• Population accessibility
• Cultural attitudes and practices
• Facilities available for delivery

The need for a vaccination programme depends on:

• Disease incidence
• Age distribution of disease
• Disease trends
• Disease complications
• Mortality
• Population / cultural attitudes
• Cost and benefit
• Political expenditure
• Vaccine efficacy and side effects
• Availability and validity of delivering
• Provision of trained primary care providers
• Vaccine type

Development of a vaccination programme

Plus: pharmo-economic studies - Cost Benefit Analysis (CBA) / Cost Effective Analysis (CEA) (at phase 3)

Implementation of a vaccination policy

• Recommendations for use of a vaccine/vaccine policy are based upon The Joint Committee of Vaccination and Immunisation (JCVI) expert opinion after reviewing all the available evidence
• The JCVI is an independent expert advisory committee whose role is to advise UK public health departments on matters relating to communicable diseases, preventable and potentially preventable through immunisation
       -  choice of policy - mass or selective
       -  publish recommendations in ‘Immunisation against infectious disease’
       -  commonly referred to as the “Green Book”
       -  license vaccine and batch release
       -  procurement of vaccine

Commissioning delivery

Media campaign, and start giving vaccinations.

Factors associated with low immunisation coverage

• socio-demographic variables
• deprived, inner city living
• mobile families
• birth order, large families
• children with chronic illnesses
• ethnicity
• personal variables
• parents
• professionals
• health service variables - generally good in the UK, but be aware of some limitations
• poor co-ordination (private and public sectors)
• unclear responses
• access to guidelines and policies

UK initiatives leading to improved coverage in 1990s

• 1986: district immunisation coordinator appointed
• 1987: rapid monitoring and feedback of coverage data - COVER statistics
• 1988: national guidelines on immunisation
• 1990: accelerated immunity schedule
• 1990: GP contracts - financial incentives
• 1992: parent-held records/Personal Child Health Record often referred to as the Red book
• National vaccination campaigns - intermittent (e.g. MMR/Hib)

Other:

• Opportunistic delivery
• Specific immunisation clinics
• Targeted information campaigns
• UK immunisation service is considered a world example
• Initiated by birth notification on 'Child Health System'
• Child Health Information Services (CHIS) computer generates automatic letters inviting children for vaccination, and ensures GP call and recall for immunisation

Vaccine Coverage

COVER (Cover of Vaccination Evaluated Rapidly)

In the UK since 1988 computerised child health records contain vaccination details of all children resident in the area. These are completed each time a vaccine is given by a healthcare professional.

Vaccine information is collected by PHE Centre for Infectious Disease Surveillance and Control (CIDSC) every 3 months from local Child Health Computer Systems detailing the number of children who have completed the vaccination schedule at 1, 2 and 5 years of age.

These data are promptly fed back to local level, creating the opportunity to improve coverage and to detect changes in vaccine coverage quickly

Public Health England also collect data via the Immform system to assess coverage of vaccinations delivered to adolescents and adults, e.g. HPV, pertussis for pregnant women, seasonal influenza. These are largely derived from an automated extraction of data held on GP systems but also includes some manual recording for vaccines delivered outside of primary care, e.g. HPV vaccine in schools. The Immform platform also provides vaccine-ordering facilities for the NHS

Uses

• Detect change rapidly and monitor trends in uptake
• Look for pockets of poor coverage
• Estimate vaccine efficacy
• Measure impact and success of a vaccination campaign
• Evaluation of Vaccine Programmes
• Disease incidence
• Susceptibility
• Vaccine Coverage
• Adverse events and vaccine safety

Monitoring Adverse Events and Vaccine Safety

• Committee on Safety of Medicines (CSM) advises the Medicines and Healthcare products Regulatory Agency (MHRA) on safety, quality and efficacy of vaccines
• MHRA responsible for Yellow Card Adverse Drug Reaction reporting system
• Yellow Card reports can signal possibility that a product may be associated with certain risks. These can then be investigated further to decide whether a side effect is truly from a vaccine or not.

United Kingdom Routine childhood Immunisation schedule 2016

© Sarah Anderson 2008, Gayatri Manikkavasagan 2008 and 2017, and Claire Cameron 2017