KRT88P and infection: In addition, seven samples from other serological groups tested positive by nucleic acid testing (NAT): two samples (5%) from the anti-HBc+/anti-HBs + group, indicating HBV DNA persistence despite serologically resolved infection; one sample (2%) from the anti-HBc–/anti-HBs + group, indicating immunity due to vaccination; and four samples (1.8%) from the seronegative group (anti-HBc–/anti-HBs–), indicating susceptibility to HBV infection in these individuals.