Presentation on theme: "EPIDEMIOLOGY AND WHO POSITION ON VACCINE VIKASH KESHRI MODERATOR : DR. ABHISHEK RAUT."— Presentation transcript:
EPIDEMIOLOGY AND WHO POSITION ON VACCINE VIKASH KESHRI MODERATOR : DR. ABHISHEK RAUT
INTRODUCTION PROBLEM STATEMENT EPIDEMIOLOGY PREVENTION AND CONTROL HEPATITIS B VACCINE WHO POSITION ON HEPATITIS B VACCINE
INTRODUTION Hepatitis 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.
PROBLEM STATEMENT WORLD: Hepatitis B is endemic in almost all part of world 60% of world population live in endemic area Estimated 2 billion people infected 360 million live with chronic infection 600,000 person dies annually as result of consequence of hepatitis B every year Estimated 25% child dies in later life as a consequence of hepatitis B infection. Vaccine coverage estimated is 69%
Problem 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 study INDIA: fall in intermediate endemicity group HBsAg 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
EPIDEMIOLOGY AGENT 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
Reservoir of infection Human being only reservoir Infection spread by cases and carrier Carrier defined as persistence of HBsAg > 6 months Resistance of virus: quite stable, can survive for days in environmental condition. Can be destroyed by sodium hypochlorite Also 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.
HOST FACTOR AGE: outcome age independent For 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 GROUPS Health care workers High risk sexual behavior Commercial sex worker Frequent blood transfusion reciepient Injectable drug users Immunocompromised individuals Infant of HBV carrier
Modes of transmission Infective materials: Blood and blood products, serous exudates, saliva, seminal and vaginal fluids, etc. Routes of transmission: 1. Percutaneous 2. sexual 3. perinatal 4. Others routes
Percutaneous routes injectable drug users Nonsexual contacts between individuals Contact with intimate objects Contact 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 routes Sexual contact with infected person Favourable 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 rare No 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 days Average 75 days HBsAg can be detected as early as 30 days and may persist for several months to years.
Clinical features Insidious onset Early symptom : malaise, weakness, anorexia Ranges from mild asymptomatic infection to fulminant hepatitis to hepatocellular carcinoma to death.
Acute hepatitis B infection Asymptomatic Or Subclinical infection Clinical infection -jaundice -flu like symptom Clinical infection -jaundice -flu like symptom Fulminant hepatitis Death Chronic Carrier Recovery Or Immunity Minimal liver Disease Chronic Hepatitis Primary hepatocellular carcinoma cirrhosis DEATH
PREVENTION AND CONTROL GOALS OF PREVENTION : to decrease prevalence of chronic carrier and chronic liver disease prevention of acute hepatitis B infection Strategies: Hepatitis B vaccination. Screening of blood, plasma, organ and semen donor. Universal precautions.
HEPATITIS B VACCINATION Active immunization Passive immunization ACTIVE IMMUNIZATION Two 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 administered Dose = 1 ml. (contains > 20 mcg. HBsAg.) costlier
Recombinant DNA vaccine Introduced in 1987 in USA. Has replaced plasma derived vaccine. Cost effective and equally effective Available as monovalent or combined vaccine Active substance: -HBsAg derived from culture of yeast or mammalian cells Adjuvant: - Alum or thiomersal Storage: -2 to 8°c - freezing avoided -vaccine survive for 7 day at 45°C and for 1 month at 37°c
Administration Age : Ideal first dose at birth ( within 24 hours) Next 2 or 3 dose according to immunization schedule Can 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 routine Older 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 required
Immunogenicity and Duration of protection Usually life long immunity Hepatitis 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 pain No 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 immunity Target 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 IMMUNIZATION Hepatitis 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 infection Time : 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 POSITION All 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 3 rd dose with -DPT 1 and DPT3 -Or 3 dose schedule with routine DPT 1, 2 and 3.
No need of booster dose Catch 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, 20 th edition page no. 186 - 189 Manson’ text book tropical disease Maxcy- rosaneu- last text book of public health heahttp://www.who.int/immunization/topics/hepatitis_b/ en/index.htmllth http://www.who.int/immunization/topics/hepatitis_b/en /index.html