Hepatitis B (HB) is a public health issue in Nigeria which the introduction of the HB vaccination through the National Programme of Immunization (NPI) in 2004 has not been able to eliminate due to various challenges. This cross-sectional study measured hepatitis B virus he(HBV) serological markers for infection and immunity among individuals of ages between 0 - 32 years which are divided to two cohorts/era namely Pre-vaccine and Vaccine era in Ile-Ife, Nigeria based on the introduction time of ...