who/v&b/avi choosing the right vaccine a brief presentation on hepatitis b & haemophilus...

WHO/V&B/AVI

Choosing the Right Vaccine

A brief presentation on hepatitis B & Haemophilus influenzae type b

infections and choosing the right vaccines to prevent them

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WHO/V&B/AVI


• 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


• 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 Vaccine: Sample EPI Schedule

Disease

BCG, OPV0, HepB1

DPT1, OPV1, Hib1, HepB2 2 Months

DPT2, Hib2, OPV2 3 Months

DPT3, OPV3, Hib3, HepB3 4 Months

Measle, Yellow Fever, OPV4 9 Months

Polio Booster 18 Months

DPT Booster 1 Year after DPT3

Age for Vaccination

At Birth

4 W

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part

betw

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2,

3,

4 m

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ths

WHO/V&B/AVI

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


• HBV Transmission– from mother to child (perinatal/vertical)– from child to child– through unsafe injections & blood

transfusions– through sexual contact

WHO/V&B/AVI


• 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


• 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


• 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

– 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

– 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.

Choosing the Right Vaccine:

The issue of a birth dose of HepB vaccine

WHO/V&B/AVI


– 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


– 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


• 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


• 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


• 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


• The spectrum of Hib diseases..contd/– Septicaemia– Septic arthritis– Osteomyelitis– Cellulitis– Pericarditis

WHO/V&B/AVI


• 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


• 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

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


• 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


• 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

• pharmaceutical

• immunological

• clinical

• regulatory

• manufacturing

• public health

WHO/V&B/AVI

Any interference?

– immunogenicity?

• reactogenicity?

• shelf-life?

• stability?

• manufacturing, supply?

antigens

preservativesadjuvants

contaminantspH

stabilizers excipients

WHO/V&B/AVI


• 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


• 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 choosing the right vaccine a brief presentation on hepatitis b & haemophilus...

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