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Choosing the Right Vaccine

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  1. Choosing the Right Vaccine A brief presentation on hepatitis B & Haemophilus influenzae type b infections and choosing the right vaccines to prevent them ************ WHO/V&B/AVI

  2. Choosing the Right Vaccine • Guiding principles for choosing to introduce a vaccine • Disease burden • Cost benefit • Affordability • Existence of a robust delivery system • Availability of a vaccine • Quality of available vaccine WHO/V&B/AVI

  3. Choosing the Right Vaccine • WHO’s Expanded Programme on Immunization (EPI) • Launched by WHO in 1974 • Initially 6 target diseases (TB, Diphtheria, Pertussis, Tetanus, Measles, Polio) • Hepatitis B added in 1991 • Hib added in 1998 (for those countries with moderate to high burden of Hib disease) WHO/V&B/AVI

  4. Choosing the Right Vaccine: Sample EPI Schedule WHO/V&B/AVI

  5. Choosing the Right Vaccine • Hepatitis B disease • hepatitis B virus (HBV) is a DNA virus whose natural host is man • hepatitis is infection of the liver by the HBV, where the virus predominantly affects the liver cells (hepatocytes) • Outcome of infection • death from fulminant hepatitis • recovery with life-long immunity • development of carrier state/chronic disease WHO/V&B/AVI

  6. Choosing the Right Vaccine • HBV Transmission • from mother to child (perinatal/vertical) • from child to child • through unsafe injections & blood transfusions • through sexual contact WHO/V&B/AVI

  7. Choosing the Right Vaccine • Global burden of HBV infection • Approximately 30% of world’s population or about 2 billion people have evidence of infection • About 350 million have chronic HBV infection • Annually about 1 million die from chronic liver disease, including cirrhosis & liver cancer • HBV infections in infants are frequently asymptomatic WHO/V&B/AVI

  8. Choosing the Right Vaccine • Hepatitis B vaccine • Two types available at present- plasma derived and DNA recombinant vaccines • But in the next few years, plasma derived HepB vaccine will be phased out • Plasma derived vaccine is a blood product whereas DNA recombinant vaccine is genetically engineered • Both are equally safe and effective • All Vaccine Fund supply is DNA recombinant WHO/V&B/AVI

  9. Choosing the Right Vaccine • Hepatitis B vaccine…contd/ • Hepatitis B vaccine is available as either only hepatitis B or in combination with other vaccines • Combinations of hepatitis B vaccine include DTP-HepB (tetravalent), DTP-HepB+Hib (pentavalent), DTP-HepB-IPV+Hib (hexavalent) & HepB-Hib WHO/V&B/AVI

  10. Choosing the Right Vaccine:The issue of a birth dose of HepB vaccine • In many countries perinatal transmission from mothers infected with HBV to their infants is a major source of HBV infections • Infections occur usually at time of births, in utero transmission is relatively rare. • Therefore, the most effective way to prevent perinatal transmission is to give hepatitis B vaccine as soon as possible after birth, preferably within 24 hours WHO/V&B/AVI

  11. Choosing the Right Vaccine:The issue of a birth dose of HepB vaccine • Where feasible, a birth dose should be administered to all infants at birth. • However, this is not a practical option in countries where a large proportion of births take place outside health facilities. WHO/V&B/AVI

  12. Choosing the Right Vaccine:The issue of a birth dose of HepB vaccine • One alternative is to screen mothers for HBsAg and give a birth dose to those children born to HBsAg positive mothers. But extensive resources are needed to screen pregnant mothers and track infants • Another option is to combine HepB vaccine with that of DTP at 6,10 & 14 weeks • With this schedule, in countries with high perinatal transmission rates, the rate of decline in prevalence of HBV infection will be slower, but may be more practical and feasible WHO/V&B/AVI

  13. Choosing the Right Vaccine:The issue of a birth dose of HepB vaccine • In countries where perinatal transmission is not a major source of infection, administration of a birth dose contributes less to overall reduction of hepatitis b infection. • In these countries, the most practical option may be to combine HepB vaccine with that of DTP at 6,10 & 14 weeks WHO/V&B/AVI

  14. Choosing the Right Vaccine:The issue of a birth dose of HepB vaccine • The decision on whether to introduce a birth dose of hepatitis b vaccine is largely a function of burden of perinatal transmission and programmatic feasibility of administration of a birth dose. WHO/V&B/AVI

  15. Choosing the Right Vaccine • Haemophilus influenzae type b diseases • Hib is a major killer - every year more than 400,000 children die due to Hib disease • Six serotypes (types a-f) known to cause disease, but type b is responsible for over 90% of life-threatening Hib infection in children • All serotypes live in nose & throat of people and usually do not cause serious disease • When they cause serious disease, it is mostly in children under five years of age WHO/V&B/AVI

  16. Choosing the Right Vaccine • The spectrum of Hib diseases • Bacterial meningitis • major cause of bacterial meningitis in children • 3% to 45% of children with meningitis die (difference in developed/developing countries) • 19-45% of children with Hib meningitis suffer neurological complications • Pneumonia • 2nd most common cause of bacterial pneumonia in children less than 5 WHO/V&B/AVI

  17. Choosing the Right Vaccine • The spectrum of Hib diseases..contd/ • Septicaemia • Septic arthritis • Osteomyelitis • Cellulitis • Pericarditis WHO/V&B/AVI

  18. Choosing the Right Vaccine • Haemophilus influenzae type b (Hib) vaccine • Hib vaccine is known as a conjugate vaccine as the bacterial capsular polysaccharide material is linked to tetanus toxoid, diphtheria toxoid, a diphtheria-like protein, or a mix of proteins from other bacteria • All are effective in preventive Hib disease WHO/V&B/AVI

  19. Choosing the Right Vaccine • There are various formulations of Hib vaccine • Liquid Hib vaccine (monovalent) • Liquid Hib combined with DTP • Liquid Hib & Hepatitis B combined vaccines • Lyophilised (freeze-dried) Hib with saline diluent (monovalent) • Lyophilised Hib vaccine to be used with liquid DTP, DTP-HepB, DTP-IPV, DTaP, or DTaP/IPV in combination WHO/V&B/AVI

  20. Choosing the Right Vaccine • Is Hib vaccine recommended for all countries? • In industrialised countries of Europe and the Americas, Hib has been in use for almost a decade now • There is enough evidence that Hib disease is a major public health problem in the Americas, Sub-Saharan Africa and the Middle East • There is limited evidence to show that Hib disease is a public health problem in Asia & Eastern Europe WHO/V&B/AVI

  21. Choosing the Right Vaccine • Combination vaccines • DTP is the earliest combination vaccine in use • In the current Vaccine Fund supplies, combinations include DTP-HepB (tetravalent) or DTP-HepB+Hib (pentavalent), • In future, it is possible to have DTP-Hib or HepB-Hib • In the industrialised countries, there are many different combinations in use WHO/V&B/AVI

  22. Choosing the Right Vaccine • Why combine vaccines? • More & more vaccines becoming available. So if combined • fewer injections, less distress to infants & parents • less visits to health facility • less injection related complications • reduced costs (lower overall cost of vaccination programme) • may simplify transportation & storage problem WHO/V&B/AVI

  23. Challenges of combined vaccines • pharmaceutical • immunological • clinical • regulatory • manufacturing • public health WHO/V&B/AVI

  24. antigens adjuvants preservatives pH contaminants stabilizers excipients Any interference? • immunogenicity? • reactogenicity? • shelf-life? • stability? • manufacturing, supply? WHO/V&B/AVI

  25. Choosing the Right Vaccine • Which vaccine to choose? • For those countries introducing only HepB vaccine without a birth dose, the best choice is a combination of DTP-HepB • For those countries with a birth dose, they may either have monovalent HepB for birth dose and a combination DTP-HepB for the rest or may continue with only monovalent HepB and DTP separately WHO/V&B/AVI

  26. Choosing the Right Vaccine • Which vaccine to choose? • For those countries introducing both HepB and Hib vaccines, the most efficient choice is the pentavalent (DTP-HepB+Hib), if there is no birth dose for infants for HepB • If birth dose of HepB is necessary, then a combination of DTP-Hib and monovalent HepB may be an alternative choice WHO/V&B/AVI