The efficacy of hepatitis B vaccination program in upper Egypt: Flow cytometry and the evaluation of long term immunogenicity.

Anti-HBs levels wanes with time. Many studies discussed the B cell response to HBV vaccine. However, the data about memory T cell response are limited. To evaluate the efficacy of hepatitis B vaccine via evaluating anti-HBs levels and HBsAg specific memory T-lymphocytes through descriptive study. The study was conducted in a tertiary care setting. This study included 440 vaccinated persons during infancy. Group I: 6 to less than 10 years old; Group II: 10 to less than 14 years old; Group III: 14 to less than 17 years old; Group IV: 17 years old. The serum samples were screened for HBV markers. Cytokines secretion by HBsAg-specific memory CD45RO(+) CD4(+) T cells was measured after in vitro culture using flow cytometry. The mean titer of anti-HBs was higher in group I in comparison to others (P-value = 0.000 for each). IFN-γ and IL-4 secreted by memory CD4(+) T cells were positive in all with anti-HBs >100 mIU/ml, while positive in 87% and 75% of participants with anti-HBs <10 mIU/ml and positive in 73% and 32% of participants with absent anti-HBs. The percentage of cells secreting IFN-γ and those secreting IL-4 were higher among participants with serum anti-HBs >100 mIU/ml than those having <10 mIU/ml or absent (P < 0.001 for each). Anti-HBs positivity decreased with time since childhood vaccination. Breakthrough infections are rare in vaccinated persons. Hepatitis-B vaccine is efficient in controlling HBV infection. Flow cytometry is a useful tool to assess the long term persistence of T cell memory after childhood vaccination. J. Med. Virol. 88:1567-1575, 2016. © 2016 Wiley Periodicals, Inc.