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A Pilot Evaluation Study of Seroconversion After Hepatitis B and Measles Vaccinations in Context of EPI in Egypt.
1Moustafa M. El-Saied, 1Ekram A. Hashem, 2Enas A.E. Daef, 2Mohammed T. Shata, 2Mohammed S. Badry, 3Esmat Mansour, Imam Z. Imam, 1Mohammed Amer M.M. Shahwan, 1Khaled Son, 2Emad Nafie and 1Farouk Hassanien.
1Departments of Pediatrics, 2Microbiology and Immunology, Faculty of Medicine, Assiut University and 3Healthy Mother/Healthy Child Project.

This study included 201 healthy infants, 2 months old (105 females and 96 males) attending for vaccination at baby clinic, Assiut University Hospital. The aim was to evaluate seroconversion after hepatitis B and measles vaccinations used in the Expanded Program on Immunization (EPI) in Egypt. Before vaccinations, venous blood samples were taken and sera were tested for hepatitis B surface antigen (HBsAg) and antibody to hepatitis B surface antigen (anti-HBs) using commercial enzyme immunoassay kits. A dose of 2.5 micrograms recombinant hepatitis B vaccine was given at two, four and six months of age with other routine childhood vaccines (DPT and Polio). At the age of 9 months. Venous blood were taken from 100 infants and sera were tested for measles antibodies by serum neutralization test. Measles vaccine was given using Edmonston strain measles virus. Nine months later, at the age of 18 months. Blood samples were similarly collected from 74 children and tested for the presence of HBsAg and quantitatively for anti-HBs. Testing for measles antibodies was only available for 68 out of the 74 children using ELISA and serum neutralization test. Out of 201 infants aged 2 months, examined before hepatitis B vaccination, 4 (1.99%) were positive for HBsAg and 22 (10.95%) were positive for anti-HBs. Out of 100 infants that attended at 9 months of age, 91 infants were positive for measles antibodies; 52 of them at a titer of 1/8 and 39 at a titer of 1/16 before measles vaccination. The rate of presence of measles antibodies was significantly lower in infants with marasmus and in those with higher index of crowding in the house (p<0.025, p<0.01 respectively) as compared to infants. At the age of 18 months, serum neutralization test were positive at a titer of 1/16 in all 68 followed up children. The magnitude of measles antibodies in terms of ELISA optical density ratios was significantly higher (p<0.01) in children negative for measles antibodies prior to vaccination than in those having prevaccination antibodies at a titer of 1/16. Out of the 74 children tested at 18 months, a low (10-100 m IU/ml) or good antibodies response (>100 m IU/ml) was found in 57 children (77.03%). Geometric mean titers were 58.97 28.65 and 136.11 31.46 m IU/ml, respectively. In conclusion, the schedule of hepatitis B vaccination in our locality yields a good rate of protective antibody seroconversion. However, trials using higher vaccine dosage and/or modified vaccination schedule need to be evaluated. Regarding measles vaccination, although the seroconversion is high, the magnitude of measles antibodies was better when no antibodies response was found in the infant was free of antibody prior to vaccination, which may suggest a trial of measles vaccination at an older age.Measles remains a serious worldwide problem. It is estimated that 1.6 million children die annually from measles and its complications (Aaby and Clements, 1989). High morbidity and mortality from measles among infants under 9 months is an obstacle to measles control in many developing countries (Cutts et al., 1995). The optimum age for vaccination depends on the rate of decline of maternal antibody on one hand, and the rate of measles infection on the other hand (Williams et al., 1995). Disappearance of maternal measles antibodies takes place at variable ages in different communities (Kuyucu et al., 1996). Delaying the age of vaccination in developing countries may be associated with high rate of natural measles infection (Rosenthal and Clements, 1993).

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Copyright 2002 Egyptian Association of Immunologists .
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