بررسي سطح سرمي پادتن هپاتيت B عليه آنتي ژن S در كودكان 7 تا 9 ساله ي واكسينه شده شهر زنجان سال 1382

Survey of Anti-HBs Serum Level in Vaccinated 7-9 Year-old Children in Zanjan City 2004

Background: Vaccination against hepatitis B has lead to satisfactory production of anti-HBs in more than 90% of the cases. Nevertheless, numerous studies have revealed a gradual decline in anti-HBs level. This study was carried out with the aim of determining anti-HBs serum level in 7-9 year-old children in Zanjan, vaccinated through routine nationwide vaccination program. Materials and Methods: Two hundred and seventy three students were selected through random multiple staged method from 10 elementary schools in Zanjan. After getting the letter of satisfaction from parents and preparing 5 ml blood sample, serum level of anti-HBs was determined using ELISA with Radium kit. All serums were also tested for anti-HBc. Data were categorized into four groups. The first group contained no antibody (0) the second <10, the third 10-100 and the forth >100 unit/ml and serum level under 10 was considered as weak response and confidence interval was estimated. Results: In 29.5% of the samples no anti-HBs was observed. In 22.5% the amount was under 10, in 27.5% between 10 and 100 in 20.5% over 100 unit/ml anti-HBs was detected. As a matter of fact 52% of the samples were under 10 and 48% contained over 10 unit/ml anti-HBs. Level of antibody decline in boys and girls was equal. One percent of the studied children had anti HBc. Conclusions: Decline in anti-HBs serum level was obvious five years after vaccination. However, this finding dose not either recommend or reject the administration of booster dose of vaccine. This decrease dose not imply potential for infection and it is possible that the subject would be able to produce antibody against the virus in case of exposure. More research including higher sample number is recommended.