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Slide 4 - Decisions to introduce a vaccine Before any vaccine can be adopted into our routine childhood immunisation programme, a number of things have to be considered. Is the disease important enough - that is, common and/or serious? An example of this was the decision to introduce MenC in 1999/2000. Meningococcal C disease is uncommon It only affects very small numbers BUT because it had: High death rates High morbidity It was a suitable candidate vaccine. Supported by epidemiology the programme was extended in 2001 to include all young adults under 25 years of age. Can a safe and effective vaccine be produced? Because the majority of vaccines are given healthy infants and young children, safety is very important. But as all vaccines have side effects, they must be shown to be: Less serious than the actual disease Less common than the risks from the diseases they are designed to prevent. As no vaccine can ever be 100% effective, it must be proved to substantially prevent diseases happening. Is the vaccine acceptable to the individual and, in the case of childhood vaccines, to their parents and carers? There must be population recognition of: The seriousness of the disease Understanding and acceptance of the method of vaccine administration Understanding and acceptance of the number of doses Understanding and acceptance of the reasons for boosters As the majority of vaccines are given by injection, supporting scientific evidence must prove: It works and prevents the disease The number of doses required The interval between the doses The number of boosters need to maintain immunity Vaccines are used in combinations, for example combined diphtheria, tetanus, whooping cough and Hib (DTP-Hib) and measles, mumps and rubella (MMR). Is the vaccine cost-effective – does it result in an overall saving of resources? Resources in any health system are always limited, so vaccines need to show that they save money in the long term by: Reduction of expense caused by illness as the disease becomes less common Reduction of care costs of the acutely sick and the permanently damaged Major reductions in suffering results in enormous saving in overall economic terms. Can enough people in the target group be immunised to make the vaccination programme effective? To prove efficacy there must be good uptake of vaccination to protect individuals in the target group Low uptake reduces the incidence of disease in the target group - BUT This may shift susceptibility from childhood to adolescents or young adults, who may have more serious implications, e.g. in Greece in 1996 where very low uptake of rubella resulted in an epidemic of congenital rubella syndrome. Reference: Childhood Immunisation The Facts. (2001) Bedford H, Elliman D. Health Promotion England, London

Slide 5 - Different types of vaccines All vaccines contain active immunising antigens that come from either the bacteria or viruses that cause infection, and stimulate the immune system to make a response. Inactivated vaccines: There are four types of vaccines in this category, protecting against bacterial infection: Killed whole micro-organism vaccine, e.g. whole cell whooping cough vaccine Inactivated bacterial toxins. These vaccines are manufactured from the toxin produced by a bacterium, which can cause serious complications - e.g. the diphtheria bacterium can be treated with antibiotics, but the toxin produced by the bacterium can cause permanent complications of the heart and central nervous system. Acellular pertussis vaccines are manufactured using certain parts of the bacterium that causes whooping cough. The polysaccharide vaccines. These are manufactured from the purified sugar coating (polysaccharide) of bacteria that cause infection. plain polysaccharide vaccines do not protect children under 2 years conjugate polysaccharide vaccines are conjugated (joined) to a small amount of a protein, such as diphtheria or tetanus, which makes the vaccine work in babies and young children. Live attenuated vaccines These vaccines are weakened forms of the “wild” virus (e.g. measles, mumps, rubella and polio) or bacterium (tuberculosis) that cause disease. Vaccines manufactured in this way cannot cause the actual disease, and neither can anyone catch any one of the diseases from a recently immunised individual. The exception to this is polio vaccine, which can, very rarely cause the disease either in the recipient or an unimmunised individual changing the nappies of a recently immunised infant. Combination vaccines. As increasing numbers of vaccines are added to the national childhood programme, combination vaccines are developed to: Minimise the number of injections needed Minimise the number of immunisation appointments. DTP-Hib and MMR are examples of vaccines protecting against several diseases, and polio vaccine contains three types of polio virus any o]f which can cause disease. Combination vaccines are just as safe and just as effective when given together as they are when given separately.

Slide 6 - Development of safe, effective vaccines Years of extensive laboratory and other types of testing takes place before a vaccine is developed for testing among humans. It then takes on average 12 years for a vaccine to be ready for use on the general population: Pre-clinical testing. This takes about 2-4 years and involves laboratory investigations and testing. Approval by relevant regulatory authorities and Ethics Review Committees is required before a candidate vaccine is allowed to be tested on human volunteers. Volunteers and protocols Clinical trials rely on volunteers who are from the age group for whom the vaccine is intended including babies and children. They must: Agree to be given the vaccine Attend follow-up for evaluation and physical testing (e.g. blood pressure, urinalysis, heart rate etc) Provide blood samples used to assess a vaccine’s safety and potential efficacy Protocols A protocol is a formal document that clearly defines: Objectives and need for the study The exact procedures to followed Requirements of the volunteer – what he/she may expect in: Side effects Potential benefits or risks from participating Named person to contact for any information during the study Consent Volunteers or their parents are required to sign consent indicating: Understanding of the study and potential risks Willingness to participate Registering their choice to withdraw consent and discontinue participation at any time without prejudice Clinical trials are carried out in three initial stages, taking on average 5-7 years. Phase I - Safety: The candidate vaccine in various doses is tested on small numbers (about 8-12) of healthy adult volunteers. Multiple Phase l studies of a particular vaccine may be conducted in different centres. Their purpose is to assess: Short term side effects including serious or unexpected adverse effects Adjust vaccine dosage Phase II – Safety and immune response: Multiple studies of several hundred volunteers may be carried out in different centres. The volunteers are from the age group for whom the vaccine is intended, e.g. testing among the elderly or babies and children. Protocols provide technical requirements and ethical approval protects the rights of the individual. The purpose of these studies is: Expand the knowledge regarding safety Testing the ability to provoke an immune response (immunogenicity) Consistency studies ensure every vaccine meets standards of absolute quality, stability and efficacy Phase III – Safety, immune response and efficacy: Efficacy studies are often carried out on thousands of individuals. The purpose of these studies is: To confirm the vaccine safely prevents disease with minimal side-effects. Evaluate a vaccine in the context of the general population The potential use of the vaccine for public health practice Licensure: The Medicines and Healthcare product Regulatory Agency (MHRA) for manufacture and distribution grant a product licence, once the vaccine has passed safety and efficacy requirements. Policy: The Joint Committee on Vaccination and Immunisation (JCVI) is an independent committee, which provide expert advice on immunisation policy and make a policy recommendation to introduce the vaccine, based on both scientific evidence and cost implications. References: Immunisation against Infectious Disease (1996) Eds. Salisbury D, Begg N. HMSO, London Vaccine development from laboratory to market and beyond. Steimles D.

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