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Choosing the Right Vaccine. A brief presentation on hepatitis B & Haemophilus influenzae type b infections and choosing the right vaccines to prevent them. ************. Choosing the Right Vaccine. Guiding principles for choosing to introduce a vaccine Disease burden Cost benefit

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choosing the right vaccine
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

choosing the right vaccine1
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

choosing the right vaccine2
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

choosing the right vaccine3
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

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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

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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

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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

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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

choosing the right vaccine the issue of a birth dose of hepb vaccine
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

slide11

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

choosing the right vaccine the issue of a birth dose of hepb vaccine1
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

choosing the right vaccine the issue of a birth dose of hepb vaccine2
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

choosing the right vaccine the issue of a birth dose of hepb vaccine3
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

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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

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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

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Choosing the Right Vaccine
  • The spectrum of Hib diseases..contd/
    • Septicaemia
    • Septic arthritis
    • Osteomyelitis
    • Cellulitis
    • Pericarditis

WHO/V&B/AVI

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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

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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

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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

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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

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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

challenges of combined vaccines
Challenges of combined vaccines
  • pharmaceutical
  • immunological
  • clinical
  • regulatory
  • manufacturing
  • public health

WHO/V&B/AVI

any interference

antigens

adjuvants

preservatives

pH

contaminants

stabilizers

excipients

Any interference?
  • immunogenicity?
  • reactogenicity?
  • shelf-life?
  • stability?
  • manufacturing, supply?

WHO/V&B/AVI

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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

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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

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