Among this sub-set, 4.5% (3 people) had anti-HBs only (evidence of immunity secondary to vaccination), 4.5% (3/66) had HBsAg (i.e. chronic hepatitis B), 13.6% (9/66) had both anti-HBc and anti-HBs (consistent with immunity through natural infection), (10.6%, 7/66) had isolated anti-HBc and 68.2% (45/66) had no hepatitis B antigens detected. This evidence concerns the gene KRT88P and chronic hepatitis B virus infection.