GSTM1 and hemoglobin measurement: Vaccination against HB in Serbia has been carried out since 2005/2006, and when it is taken into account that the seroprevalence cross-section was made in 2015–16, this means that the vaccinated generations were covered 18–19 years ago, and this coincides with the high anti-HB levels found in the age group of 1–19 years.