[IMPACT OF THE IMMUNIZATION PROGRAM INTEGRATED TO THE EXPANDED IMMUNIZATION PROGRAM(EPI) IN HUANTA,1994-1997]
INTRODUCTION: Huanta is an interandean valley at 2,400 meters above sea level in the peruvian highlands. It is hyperendemic for HBV, and deaths related to HBV such a fulminant hepatitis, cirrhosis and hepatic carcinoma make up 8% of the total mortality. A pilot program of inmunization against HBV integrated with the Expanded Immunization Program (EPI) was established in 1994, so as to limit the incidence if HBV-HDV, and as a strategy to improve EPI coverages.MATERIALS AND METHODS: A total of 1,412 children under 1 year old and 5,175 children from 1 to 4 years old were scheduled for vaccination. Three doses of the recombinant DNA vaccine agains HBV were used for each child. The schedule was adapted to the EPI vaccination calendar. In children under a year the schedule was: newborns: BCG, Polio, HBVI; 2 months: Poliol DPTI, HBV2; 3 months: Polio 2, DPT2; 4 months: polio 3, DPT3, HBV3; 9 months: Measles. In the group of children from 1 to 4 years old, the schedule was: HBVI at child recruitment; HBV2: after 2 months of the first one, HBV3: after 6 month of the first one.RESULTS: One year after starting, 3 dose immunizations have been made in 1,386 (98.1%) children under one year old and 4,353 (84.1%) in children from 1 to 4 years old. No important side effects related to the HB vaccine have been recorded; one case of HAV and two of HBV occurred in children who were beginning their immunization schedule. The objective of improving vaccination coverage by the EPI was achieved; the coverage in children under one year old for DPT were 76% (1991), 64.5% (1992), 55.2% (1993), and as a result of the strategy the coverage was improved to 98.1%. The program efficacy is demonstrated by the significative reduction of the infection rates of children 3-4 years old in 1994 (24.4-30.4%) compared with the children infection rates of the same age in 1997 (2.3-5.1 %).CONCLUSION: Including the HBV vaccine within the EPI program in a hyperendemic area for HBV-HDV has improved the EPI coverages; the vaccination compaign strategy has shown its effectiveness and safety, showing impact in the reduction of infection rates.