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Hepatitis B Vaccination in Bangladesh: a Suggestion Based on Current Evidence

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Author(s): Harunor Rashid MBBS | Shafquat Mohammed Rafiq

Journal: Hepatitis Monthly
ISSN 1735-143X

Volume: 6;
Issue: 1;
Start page: 41;
Date: 2006;
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ABSTRACT
IntroductionThe hepatitis B virus (HBV) causes up to a million deaths worldwide and 16 million health care related infections in the tropics each year(1,2), and over 350 million become chronically infected carriers who have no significant liver disease; approximately three quarters of them are in Asia and the western pacific region(3,4). HBV infection is a potentially life threatening condition as many of the affected individuals progress to chronic hepatitis,cirrhosis and hepatocellular carcinoma (HCC)(3). In infants and children, acute hepatitis B infection is nearly always asymptomatic, whereas in adults it is usually the opposite. But on the other hand, the risk of becoming chronic carriage is much greater in children than in adults; as many as 90% of infants born to Hepatitis B e Antigen (HBeAg) positive mothers become carriers themselves and, therefore, in long term are more likely to developchronic liver disease(5). Currently, though several antiviral drugs are used,there is no reliable curative treatment for HBV once it has been acquired and prevention by universal immunization remains the strategy for reducing the number of acute infections, chronic carriage and the long-term burden from diseases such as HCC(4,6). In 1991, in an attempt to reduce the global impact of HBV infection, WHO recommended that hepatitis B vaccination should be integrated into national immunization programs in all countries(7).Some Asian countries, for instance, Thailand, haveadopted the policy of immunizing children universally against the disease as early as 1992, however many others lagged behind(4).The true prevalence of Hepatitis B in Bangladesh is yet to be ascertained by a reliable study. Data available from different studies show that it ranges between 0.8 and 5.4% depending on the study design, samples and laboratory methods used(8-10).These data were based on detection of HBsAg antigen; the rates would have been higher, had they been based on anti-HBc antibody(11). Relying on these statistics Bangladesh can be categorized as an intermediate endemic zone for HBV(12). Unfortunately, despite an increased prevalence of HBV infection, the country has not incorporated hepatitis B vaccination into its national childhood immunization policy until recently, most probably because of its economic constraints. Presently it offers three doses hepatitis B vaccine to all babies. It is felt that the current regimen was drawn in on the basis of ongoing uncertainties and disagreements surrounding the vaccine all over the globe.Uncertainties Surrounding HBV ImmunizationThe rationale of HBV immunization is illustrated in the box; however uncertainties surrounding HBV immunization do exist, these are:Box: Rationale of Hepatitis B Immunization The rationale of HBV vaccination is to prevent: · Episodes of acute hepatitis B · Chronic hepatitis B surface antigenaemia · Chronic hepatitis and the need for therapy · Hepatocellular carcinoma · HBV transmission Correspondence:Dr. Harunor Rashid, Research Fellow, Academic Departmentof Child Health, Queen Mary University of London, 38 NewRoad, London, E1 2AX, UKFax: +44(0)2073777167E-mail: h.rashid@qmul.ac.ukHep Mon 2006; 6 (1): 41-44 - Duration of vaccine- induced immunity:It has been shown that immunization with three doses of HBV vaccine provides acceptable level of seroprotection for at least five years(13). Titersdecreased to 99% of the 14 year olds had titers of |“|10mIU/mL while one year after the booster 10mIU/mL after 1 month of first, second and third vaccinations were 58%, 70% and 94% respectively(16). However, it has been observed in other studies that two doses of recombinant HBV vaccine given over 4 or 6 months provide adequate seroprotection (|“|10mIU/mL) in |“|95% of adolescent vaccines(13,17). There were small variations in vaccine response between infants and teenagers. The range of protection for different doses is shown in Table(17). If we accept that a level of 80-95% seroprotection is sufficient for Bangladesh then a strategy with only two doses would be more economical.Table: Percentage of infants and teenagers/adults responding to 1, 2 or 3 doses of HBV vaccineDose # Infants Teens and adults 1 16-40% 20-30% 2 80-95% 75-80% 3 98-100% 90-95% [Adapted from Margolis H et al. (copy right free resource)17]- Acceptability of a universal program:The data available from WHO reveal that the uptake of other vaccines in routine immunization schedule can vary in Bangladesh from 83% for DPT3 (Diphtheria-Pertussis-Tetanus vaccine) to 95% for DPT1 (18).Utilizing this experience we may suppose that the acceptability of HBV vaccine will be somewhere between 80 and 95%. The uptake can be increased by improving health education, creating awareness among people in general and among health care providers in particular as well as involving politicians and religious leaders in the vaccination campaign. There were concerns that HBV vaccine could be related to central nervous system demyelinating disorders. However, a later study in France concluded that in the worst case considered the number of complications prevented by vaccination outweighs quantitatively the potential risks(19).- Vaccine Failure:A small percentage of adults fail to mount an immunological response despite completion of the immunization schedule. The variables associated with vaccine failure are: site of vaccination, obesity, smoking, presence of diseases that alter immune system, medications, age (>40 years) and male sex(17,20). Preterm babies

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