RESUMEN
Background & objectives: Safe blood and blood products should be offered to all patients in need for blood transfusion. The objectives of the present study were to establish prevalence estimates for hepatitis B and hepatitis C virus infections as a foundation for safe blood transfusion in rural Vietnam, and to check the accuracy of the laboratory analysis used for hepatitis testing of blood donors in Vietnam. Methods: A cross-sectional study was conducted in two rural communities in Quang Tri, Vietnam. A total of 1,200 blood samples collected from potential blood donors were tested by an enzyme immunoassay technique (EIA) for detection of hepatitis surface antigen (HBsAg), antibodies to hepatitis B core antigen (anti-HBc), and antibodies to hepatitis C antigen (anti-HCV). The EIA test outcome was validated by a chemiluminescent micro particle immunoassay technique (CMIA). Results: The prevalence of HBsAg and anti-HBc in the study population was 11.4 per cent (95% CI 9.6 - 13.2) and 51.7 per cent (95% CI 48.8 - 54.5), respectively, the prevalences being higher in males than females. The prevalence of anti-HCV was 0.17 per cent. The test agreement between the EIA and CMIA techniques was high both for HBsAg detection (κ = 0.91; 95% CI: 0.83 - 0.99) and for anti-HBc detection (κ = 0.89; 95% CI 0.81 - 0.97). Compared to CMIA results, the positive and negative predictive values of the EIA tests were found to be 94.9 per cent (95% CI 87.5 - 98.6) and 97.5 per cent (95% CI 86.8 - 99.9) for HBsAg, and 92.4 per cent (95% CI 84.2 - 97.2) and 100 per cent (95% CI 91.2 - 100) for anti-HBc. Interpretation & conclusions: The study shows that hepatitis B virus infection is endemic in rural areas of Vietnam and that almost half of the population is or has been infected. Hepatitis C infection is rare, but false negative test results cannot be ruled out. Also, the results indicate that the EIA performance in blood donor screening in Vietnam may be sub-optimal, missing 2.5 per cent of hepatitis B virus carriers and falsely excluding more than 7 per cent of blood donors. As the prevalence of hepatitis B infection is high, occult hepatitis B infection may represent a threat to safe blood transfusion. Therefore, nucleic acid amplification testing for HBV should be considered for blood donor screening in Vietnam.
RESUMEN
We report the coverage, safety, and logistics of a school-based typhoid fever immunization campaign that took place in Hue City, central Vietnam; a typhoid fever endemic area. A cluster-randomized evaluation-blinded controlled trial was designed where 68 schools (cluster) were randomly allocated the single dose Vi polysaccharide vaccine (Typherix) or the active control hepatitis A vaccine (Havrix). A safety surveillance system was implemented. A total of 32,267 children were immunized with a coverage of 57.5%. Strong predictors for vaccination were attending primary schools, peri-urban location of the school, and low family income. Human resources were mainly schoolteachers and the campaign was completed in about 1 month. Most adverse events reported were mild. Safe injection and safe sharp-waste disposal practices were followed. A typhoid fever school-based immunization campaign was safe and logistically possible. Coverage was moderate and can be interpreted as the minimum that could have been achievable because individual written informed consent procedures were sought for the first time in Hue City and the trial nature of the campaign. The lessons learned, together with cost-effectiveness results to be obtained by the end of follow-up period, will hopefully accelerate the introduction of Vi typhoid fever vaccine in Vietnam.