Comparison of subgroups Ib and IIb in respect to the IL-12A and IL-12B polymorphic variants showed that patients who developed anti-HBs in response to hepatitis B vaccination showed higher frequencies of GA rs568408 IL-12A (adjusted OR 2.4, 95 % CI 1.2–4.9, P = 0.015) and GA/AA (adjusted OR 2.5, 95 % CI 1.3–5.0, P = 0.007), and a lower frequency of GG rs568408 IL-12A (adjusted OR 0.4, 95 % CI 0.2–0.8, P = 0.007) compared to any other examined genotypes of IL-12A. This evidence concerns the gene IL12A and hepatitis B virus infection.