Hepatitis B virus vaccination of voluntary blood donors and immunization status assessment by Anti-Hepatitis B Surface (HBs) antibody titer.

Sir,

The study was conducted at the Prathama Blood Centre, Ahmedabad from 14/06/2009 to 31/03/2010. In our study hepatitis B virus (HBV) negative voluntary blood donors were enrolled and vaccinated. The sero-conversion rate was determined by anti- Anti-Hepatitis B Surface HBs-antibody titer measurement on a small numbers of vaccines’ who received all three doses.

All blood donors were thoroughly assessed with detailed history including past exposure or jaundice. The HBV infection status was also confirmed by Hepatitis B Surface Antigen HBsAg antigen testing by Biorad Enzyme Linked Immuno Sorbent Assay ELISA kits on automated Evolis system, Biorad, USA along with Hepatitis B Virus DNA testing on Cobas s 201, Roche, USA by Taqscreen test kit. For HBV vaccination, recombinant hepatitis B vaccine of Bharat Biotech International Limited, Hyderabad (India) was used. For post-hepatitis B vaccination titer assessment, 2 ml of blood sample was collected in a plain vacutainer and anti HBsAg antibody (anti HBsAg antibody) titration was done by microparticle enzyme immunoassay (MEIA), Abbott, Germany.

A total of 4036 (3990 male and 46 female) voluntary blood donors with mean age of 35.5 years (ranged between 22 years and 59 years) were studied. All enrolled donors were HBsAg non-reactive by the ELISA method and among them 446 donors were also found negative for HBV DNA by Polymerase chain reaction (PCR) method.

Anti-HBs antibodies titers were done on limited number of donors who had completed all three HBV vaccination doses. All of the samples were collected between 1 month and 3 months of last (3rd) dose of hepatitis B vaccination. Of 4036 vaccines’, 2555, 894 and 587 donors were received one, two and three doses respectively. Out of 587 donors who received all three doses were called for anti HBsAg antibody testing but only 40 donors were reported. Of these 40 vaccinated donors, 38 (95%) donors had >1000 mIU/ml anti HBs antibody titer, while two (5%) donors samples had low titer, 1.4 mIU/ml and 10.4 mIU/ml, respectively. These two donors were recalled and revaccinated again on the counseling day and advised to return after 1 month for a repeat test. The antibody response to HBV surface antigen (anti-HBs) is an important serological marker for vaccine induced immunity to HBV.[1]

The immune response to specific antigens is a complex system with high variability between individuals, the antibodies were directed against a variety of epitopes present in variable concentrations.[2] An adequate vaccine response is defined as an anti HBs level ≥100 mIU/ml 4 weeks after the last dose. Vaccinated individuals with anti HBs level <20 mIU/ml should receive a booster dose and should be tested 4 weeks in order to know whether they were true responders or not.[3]

We concluded that “immunization” does not fight against accidental exposure” rather it prevents vaccines’ from being infected if exposed. Voluntary blood donor HBV vaccination is the right approach to prevent this infection.