HBV infection status with regard to gender, age, type of work, and length of service of the HCWs was assessed based on seropositive rates of HBsAg as a marker of current infection, anti-HBc as evidence of current or past exposure to HBV, and ‘infection-resolved’ or ‘non-isolated’ anti-HBs as a marker of natural boosting by repeated infection. This evidence concerns the gene KRT88P and infection.