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EPIDEMIOLOGY AND WHO POSITION ON VACCINEVIKASH KESHRIMODERATOR : DR. ABHISHEK RAUT

HEPATITIS B1INTRODUCTIONPROBLEM STATEMENTEPIDEMIOLOGYPREVENTION AND CONTROLHEPATITIS B VACCINEWHO POSITION ON HEPATITIS B VACCINE2INTRODUTIONHepatitis b initially called as serum hepatits is an acute systemic illness with major pathology in liver.Besides 2 billion infected cases world wide approximately 36 millions live with chronic infection.These chronically infected people are at increased risk of death from cirrhosis of liver or hepatocellular carcinoma. 3PROBLEM STATEMENTWORLD:Hepatitis B is endemic in almost all part of world60% of world population live in endemic areaEstimated 2 billion people infected360 million live with chronic infection600,000 person dies annually as result of consequence of hepatitis B every yearEstimated 25% child dies in later life as a consequence of hepatitis B infection.Vaccine coverage estimated is 69%

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6Problem statement cont..SEAR:Estimated one third population in the region infected 80 million carrier Estimated 200,000 death occur annually vaccine coverage 41% according to 2008 WHO-UNICEF antigen studyINDIA: fall in intermediate endemicity groupHBsAg prevalence between 2% to 7%.Estimated 43-45 million cases per year.40 million carriers.100,000 death annually by disease related to HBV infection.Of 25 million newborn annually, 1 milion runs lifetime risk of HBV infection

7EPIDEMIOLOGYAGENT FACTOR:Agent : Hepatitis B virus belongs to hepadenavirdae family.Complex 42 nm. Double stranded enveloped DNA virus.Also known as Dane particle.Has affinity for liver and hepatocytes

8Reservoir of infectionHuman being only reservoirInfection spread by cases and carrierCarrier defined as persistence of HBsAg > 6 months

Resistance of virus:quite stable , can survive for days in environmental condition.Can be destroyed by sodium hypochloriteAlso by autoclaving for 30 to 60 minutes.

Period of communicability: from incubation period upto disappearnce of HBsAg and upto appearance of antibody.But can be years.

9HOST FACTORAGE:outcome age independentFor acute Hepatitis B occurs in 1% perinatal, 10% early childhood (1-5 yrs.) and 30% in older children (>5 yrs. Age)Development of Chronic hepatitis is inversely proportional to age

HIGH RISK GROUPSHealth care workersHigh risk sexual behaviorCommercial sex workerFrequent blood transfusion reciepientInjectable drug usersImmunocompromised individualsInfant of HBV carrierModes of transmissionInfective materials:Blood and blood products, serous exudates, saliva, seminal and vaginal fluids, etc.

Routes of transmission:1. Percutaneous 2. sexual 3. perinatal4. Others routesPercutaneous routesinjectable drug usersNonsexual contacts between individualsContact with intimate objectsContact of open skin or mucous membrane with infected materials.Occupational exposure: needlestick injury, surgical procedure, handling infected materials.Rituals: circumcision, tatooing, nose and ear piercing.Sexual routesSexual contact with infected personFavourable factors: -Contact with a person during active infection - H/O sexually transmitted disease - promiscuosity - Male homosexuals perinatal route:important contributor of high prevalence of infection Mostly around perinatal period. Acute infection during third trimester increases risk. In utero transmission very rareNo evidence of transmission via breast feeding

Other routes:Interpersonal contact specially childhood. May be because of skin to skin contact.

INCUBATION PERIOD:Varies from 30 to 180 daysAverage 75 daysHBsAg can be detected as early as 30 days and may persist for several months to years.15Clinical featuresInsidious onset Early symptom : malaise, weakness , anorexiaRanges from mild asymptomatic infection to fulminant hepatitis to hepatocellular carcinoma to death. EXPOSUREAcute hepatitis B infectionAsymptomaticOr Subclinical infectionClinical infection-jaundice-flu like symptom

Fulminant hepatitisDeath ChronicCarrierRecoveryOr ImmunityMinimal liver Disease Chronic Hepatitis Primary hepatocellular carcinomacirrhosisDEATHPREVENTION AND CONTROLGOALS OF PREVENTION:to decrease prevalence of chronic carrier and chronic liver diseaseprevention of acute hepatitis B infectionStrategies:Hepatitis B vaccination.Screening of blood, plasma, organ and semen donor.Universal precautions.

18HEPATITIS B VACCINATIONActive immunizationPassive immunizationACTIVE IMMUNIZATIONTwo types of vaccine available 1. Plasma derived vaccine 2. Recombinant DNA vaccine PLASMA DERIVED VACCINE:Based on HBsAg derived from plasma of human carrier.Formalin inactivated Intramuscularly administeredDose = 1 ml. (contains > 20 mcg. HBsAg.)costlier

19Recombinant DNA vaccineIntroduced in 1987 in USA.Has replaced plasma derived vaccine.Cost effective and equally effectiveAvailable as monovalent or combined vaccineActive substance: -HBsAg derived from culture of yeast or mammalian cells Adjuvant: - Alum or thiomersalStorage: -2 to 8c - freezing avoided -vaccine survive for 7 day at 45C and for 1 month at 37c

20Administration Age : Ideal first dose at birth ( within 24 hours)Next 2 or 3 dose according to immunization scheduleCan be given at any age No. Of doses: 3 or 4 First at birth , second and third with DPT1 and DPT3. First at birth, second, third and fourth with DPT and OPV routineOlder child and adults 3 doses at day o, 1 month, 2 month no need of booster dose.Dose : - 0.5 ml. for child < 10 years - 1 ml. For adults Route : - intramuscularly Site : - left upper arm for adults - anterolateral thigh for young infants Hepatitis B vaccine in immunocompromised state: - not contraindicated but special attention requiredImmunogenicity and Duration of protectionUsually life long immunityHepatitis B or even chronic carrier stage rarely occur.Role of natural booster by sub- clinical infection is yet to be proved

Adverse reaction: infrequent and rare Myalgia , transient fever , local painNo serious adverse effect Very rarely anaphylactic reaction No relation with G.B. syndrome or multiple myeloma GACVS recommends excellent safety profile Contraindications:H/O allergic reaction to component of vaccine.Pregnancy and lactation no contraindication. HIV positive individual and premature babies can be given vaccine

CATCH UP STRATEGY:Vaccinate older children and adults in low and intermediate endemicity area for population immunityTarget age specific cohort and high risk individual Strategy may be mandatory vaccination at school and college entry and before joining job.Target strategic point i.e. STD clinics, centre for IDUs.Continuous surveillance.

PASSIVE IMMUNIZATIONHepatitis B immunoglobulin used for temporary post-exposure prophylaxis.Combined active and passive vaccination better in following cases: - Newborn of HBsAg +ve mother specially if baby +ve - Percutaneous exposure -Sexual exposure - After liver transplant in case of recurrent HBV infectionTime : within 6 hours of exposure and maximum upto 48 hours.Dose: 0.05 to 0.07 ml. / kg. body weight.Provides short term passive immunity for 3 months.

WHO POSITIONAll newborn should receive birth dose of hepatitis B within 24 hours of birth, in all countries irrespective of their immunity status.Immunization programme must include HBV.Proper Reporting and monitoring MCH care needs to be strenghthened Schedule include : - First birth dose within 24 hours of birth , followed by either -2 dose schedule with 2 nd and 3rd dose with -DPT 1 and DPT3 -Or 3 dose schedule with routine DPT 1 , 2 and 3.

No need of booster doseCatch up compaign for older age group is important in intermediate and low endemicity area.Catch up compaign for infants and young children is important in high endemicity area. Other target group for catch up strategy can be high risk group.GACVs confirms excellent safety profile.WHO recommends all countries should develop goal for HBV control according to their epidemiological situation

References Park k., text book of preventive and social medicine, 20th edition page no. 186 - 189Manson text book tropical diseaseMaxcy- rosaneu- last text book of public healthheahttp://www.who.int/immunization/topics/hepatitis_b/en/index.htmllthhttp://www.who.int/immunization/topics/hepatitis_b/en/index.html

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