PPIB and hepatitis A virus infection: At T1 (pre-vaccination), T2 (post-second dose), and T3 (post-third dose), five hepatitis B serological markers (HBsAg, HBsAb, HBeAg, HBeAb, and HBcAb) were longitudinally monitored in 10 volunteers, while at T4 (4-year follow-up), monitoring was conducted in 9 volunteers (Table 1).