Presenter ITODO EWAOCHE Hepatitis B Vaccines Presenter ITODO EWAOCHE UNIVERSITY OF CALABAR

Prepared by ITODO EWAOCHE Hepatitis B Vaccines Prepared by ITODO EWAOCHE UNIVERSITY OF CALABAR

Hepatitis B Vaccines Available since 1981 Composed of HBsAg Elicits development of neutralizing antibodies to HBsAg Confers protection from infection Plasma-derived and recombinant formulations Hepatitis B Vaccine - Overview Hepatitis B vaccines have been commercially available since 1981. The vaccines are composed of HBsAg conjugated to (an adjunct of) alum. The vaccine elicits the development of neutralizing antibodies to HBsAg, anti-HBs, and these antibodies confer protection from natural HBV infection. Two types of hepatitis B vaccines are available, plasma-derived and recombinant. Plasma-derived vaccines have been available since 1981, and recombinant since 1986.

Who should be vaccinated? Adults at Risk for HBV Infection Sexual exposure sex partners of HBsAg-positive persons sexually active persons not in a long-term, mutually monogamous relationship persons seeking evaluation or treatment for STDs men who have sex with men

Adults at Risk for HBV Infection Percutaneous or mucosal exposure to blood Current or recent IDU Household contacts of HBsAg+ persons HCWs and public safety workers at risk for exposure to blood or contaminated body fluids Persons with end-stage renal disease

Adults at Risk for HBV Infection Other groups International travelers to regions with high or intermediate HBV endemicity persons with HIV infection

Dose schedules Generally, 3 doses recommended First Injection - At any given time Time 0 Second Injection - At least one month after the first dose 4 weeks Third Injection - Six months after the first dose 6 months

Childhood vaccination All children in areas of high endemicity In Nigeria vaccine introduced in 2004 Pentavalent with DPT Schedule 6 weeks, 10 weeks, 14 weeks

In high endemicity Birth dose vaccine recommended Not currently in Nigeria due to combination vaccine

Immunogenicity and Efficacy of Hepatitis B Vaccines

Immunogenicity of Hepatitis B Vaccine Protective response to vaccine defined as an anti-HBs titer >10 mIU/ml Seroconversion rates >95% after three doses of vaccine Immunogenicity of Hepatitis B Vaccine The protective effect of hepatitis B vaccine is related to the development of neutralizing antibodies to HBsAg, anti-HBs. A protective response to hepatitis B vaccine is defined as the development of an anti-HBs level >10 mIU, measured by enzyme immunoassay. Seroconversion rates of >95% after three doses of vaccine are typically seen in infants and children, with similar rates among recipients of plasma-derived and recombinant vaccines. Concurrent administration of HBIG at birth does not interfere with the antibody response to the vaccine.

Factors Associated with Decreased Immunogenicity of Hepatitis B Vaccine Major Factors Older age Immunosuppressive illnesses (HIV infection, chronic liver disease, chronic renal failure, diabetes) Obesity Smoking Minor Factors Factors Associated with Decreased Immunogenicity of Hepatitis B Vaccine Factors associated with decreased immunogenicity of hepatitis B vaccine include older age, having an immunosuppressive illness such as HIV infection, chronic liver disease, chronic renal failure, and diabetes, and taking immunosuppressive medication such as chemotheraputic agents and steroids (data for these?). Obesity and smoking have also been found to decrease the immunogenicity of vaccine. Need refs.

Efficacy of Hepatitis B Vaccines Pre-exposure prophylaxis Efficacy in preventing HBV infection ~95% if vaccinated before exposure Post-exposure prophylaxis Efficacy in preventing perinatal infection ~95% if vaccinated within 12-24 hours of birth Efficacy of hepatitis B vaccine similar when given with and without HBIG

Long-Term Protection with Hepatitis B Vaccine Vaccine provides long-term protection Immunity persists despite loss of anti-HBs Booster doses of hepatitis B vaccine NOT currently recommended Long-Term Protection of Hepatitis B Vaccine

Mechanism of Long-Term Protection with Hepatitis B Vaccine Primary vaccination series Immune memory Anamnestic antibody response Rapid rise in anti-HBs Protection from infection Exposure to HBV Long-Term Protection of Hepatitis B Vaccine

Effectiveness of Routine Infant Hepatitis B Immunization Programs

Effectiveness of Hepatitis B Vaccination Programs Routine infant hepatitis B immunization programs decrease: Incidence of acute hepatitis B Prevalence of chronic HBV infection Incidence of hepatocellular carcinoma

Prevaccination Serologic Testing Not indicated before routine vaccination of infants or children Recommended for all persons born in Africa, Asia, the Pacific Islands, and other regions with HBsAg prevalence of 8% or higher household, sex, and needle-sharing contacts of HBsAg-positive persons HIV-infected persons Consider for Groups with high risk of HBV infection (MSM, IDU, incarcerated persons)

Postvaccination Serologic Testing Not routinely recommended following vaccination of infants, children, adolescents, or most adults Recommended for Hemodialysis patients Immunodeficient persons

Management of Nonresponse to Hepatitis B Vaccine Complete a second series of three doses Should be given on the usual schedule of 0, 1 and 6 months Retest 1-2 months after completing the second series

Prevention of Perinatal Hepatitis B Virus Infection Begin vaccination within 12 hours of birth Hepatitis B vaccine (first dose) and HBIG at different sites Complete vaccination series at 6 months of age Test for response after completion of at least 3 doses of the HepB series at 9 through 18 months of age

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