Early and long term anamnestic response to HBV booster dose among fully vaccinated Egyptian children during infancy

Publication date: Available online 9 March 2018
Source:Vaccine
Author(s): Iman I. Salama, Samia M. Sami, Zeinab N. Said, Somaia I. Salama, Thanaa M. Rabah, Ghada A. Abdel-Latif, Dalia M. Elmosalami, Rehan M. Saleh, Aida M. Abdel Mohsin, Ammal M. Metwally, Amal I. Hassanin, Hanaa M. Emam, Samia A. Hemida, Safaa M. Elserougy, Fatma A. Shaaban, Walaa A. Fouad, Amira Mohsen, Manal H. El-Sayed
ObjectiveTo evaluate early and long term anamnestic response to a booster dose of HBV vaccine among non-seroprotected children.Subjects and methodA national community based project was carried out on 3600 children aged 9 months to 16 years, fully vaccinated during infancy. They were recruited from 6 governorates representing Egypt. It revealed that 1535 children (42.8%) had non sero-protective anti-HBs (<10 IU/L) and were HBsAg or anti-HBc negative. A challenging dose of 10 μg of mono-valent Euvax HBV vaccine was given to 1121/1535 children. Quantitative assessment of anti-HBs was performed to detect early (2–4 weeks) and long term (one year) anamnestic responses.ResultsEarly anamnestic response developed among 967/1070 children (90.3%).Children having detectable anti-HBs (1–9 IU/L) significantly developed early anamnestic response (90%) compared to 85% with undetectable anti-HBs (<1 IU/L), P < 0.001. Multiple logistic analysis revealed that undetectable anti-HBs, living in rural residence and children aged 15–16 years were the most significant predicting risk factors for the absence of early anamnestic response (<10 IU/L), with AOR 2.7, 2.7 & 4.7 respectively. After one year, long term anamnestic response was absent among 15% of children who previously showed early response. Poor early anamnestic response and undetectable pre-booster anti-HBs were the significant predicting risk factors for absent long term anamnestic response, with AOR 18.7 & 2.7 respectively.ConclusionImmunological memory for HBV vaccine outlasts the presence of anti- HBs and HBV vaccination program provides effective long term protection even in children showing waning or undetectable concentrations of anti-HBs. This signifies no need for a booster dose especially to healthy children.



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