The use of HBsAg is cheaper and is more specific since only 50% of patients with past HBV (anti-HBc-positive) and virological reactivation during the monitoring (HBV DNA-positive) develop the serological reactivation (HBsAg seroreversion), which is the only virological condition constantly associated with the clinical hepatitis [28]. The gene discussed is KRT88P; the disease is hepatitis A virus infection.