Mutationer i den HBV- polymerase, der koder for lamivudinresistenssubstitutioner, kan forårsage sekundære substitutioner, inklusive entecavir- associerede resistenssubstitutioner (ETVr).
Resistance and specific precaution for lamivudine-refractory patients: mutations in the HBV polymerase that encode lamivudine-resistance substitutions may lead to the subsequent emergence of secondary substitutions, including those associated with entecavir associated resistance (ETVr).).