Alternatives for completing immunization schemes against hepatitis b in peru

Alternatives for completing immunization schemes against Hepatitis B in Peru
By Edgar Pozo Ore

Hepatitis B is still an issue in Peru. The health authorities have invested a considerable amount of money to immunize the people from 2 to 19 years old against this disease in 2008. However, just half of this group has completed the vaccination series across the country. This has brought a concernabout the protection of those partially immunized and the ones that missed the vaccination. This is actually a real problem since the risk of HVB is still latent in areas of highly endemic proportions. Certainly, the Peruvian National Immunization Advisory Board as a consultative health unit has the role of providing inputs in this regard. Attending this concern, the following paper focuses oncontributing in the issue. The final goal is to identify a potential immunization alternative upon the ones that were the most adequate. The given assessments are evaluated in terms of their economic and applicability to the context matter of the problem. The paper is structured in a brief summary of the current situation, to after continue with the description of each policy alternative and thenfinally discuss in detail their pros and cons and the recommendations to overcome the problem. The proposed vaccination policy options are 1) continuing with the status quo, 2) apply universal vaccination in hyper endemic areas and 3) Apply the new two-dose vaccine schedule to target teenagers. In 1990, the prevalence of active Hepatitis B in Peru was estimated to be 3.8% in all ages (3.4% in adultsand 4.2% in children).1 Cities like Lima historically have a low prevalence, estimated to be 1.5% in 1990.2 More recent studies show that prevalence in Lima to be as low as 0.39 to 0.95% for Hepatitis B surface antigen (HBsAg), the marker for acute or chronic infection, and 3.53 - 4.51% for Hepatitis B core antibodies

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(HBcAb), a marker of past infection. These measures were 0.67% and3.53% respectively among pregnant women.3 In the Peruvian Amazon, a high prevalence area, HBsAg ranges from 3.9 to 12.1% and HBcAb ranges from 69 to 74%. HBcAb prevalence is cumulative over a lifetime of HBV exposure; 2 to 5 year olds are just 35 to 40% positive; 11 to 20 year olds are 55% positive.4 38% of infants who were born to HBsAg positive mothers and who
were not infected in the perinatalperiod became infected by age 4 years.5

Infection with HBV acutely kills 0.5% to 1.5%, with highest rates in adults older than
606. Acute infection alone accounts for 4,398 disability adjusted life years (DALYs).
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Even more significant are the effects of chronic HBV infection. After decades 30 to 40% of carriers develop liver cirrhosis and 1 to 5% of cirrhotic people develop liver cancereach year.8 Gastrointestinal diseases are the second leading cause of death in Peru with cirrhosis (17.9 deaths per 100,000 in 2006) and liver cancer (1.98 per 100,000) among the top killers.9 respectively.11 In Peru, most of the institutional efforts against HBV target infants because of the high risk of developing chronic infection (90%) which could lead to high consequences on morbidity,mortality, and economic costs. Vaccination was initiated in hyper endemic areas in 1996 and then expanded to cover all infants in 2005 through the so called “Programa Nacional de Inmmunizacion” (Expanded Program of Immunization - EPI). Doses are given at 2, 4, and 6 months of age.12 The increased risk of becoming a chronic HBV carrier persists through childhood (30% - 50% for children less than age 5).
Inadults 5% to 15% develop chronic infection.
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This accounts for 78,883 and 25,322 DALYs lost

The initial infection is typically

asymptomatic for infants under 1 year old as well as in greater than 50% of adults.14 Households’ contacts of infected individuals are at high risk. In order to protect the

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cohort of young people who are too old to benefit from EPI, but...