To the editor:
All patients on hemodialysis with negative serology for hepatitis B virus must receive the vaccine.1-4
In 1989, we initiated a vaccination protocol for patients on hemodialysis. A double dose of Engerix B® was intramuscularly administered in the deltoid muscle on months 0, 1, and 6. We annually measured the antibody levels and revaccinated with double doses those patients who did not respond or if the antibody levels were < 10 mIU/mL.
The anti-HBs antibodies were measured with a Microparticles Enzymeimmune analysis (MEIA). We defined seroconversion in the presence of an antibody titer > 10 mIU/mL.
The protocol was maintained until 2003. That year we changed to 4 double doses of the vaccine. The patients that were in the previous protocol of 1989 went on unchanged.
In this population the response rate is low, sometimes lower than 50%. Some patients maintain only the protection for short periods and it is recommended to annually determine the antibody levels. Some authors use other vaccination programs or administer co-adjuvants to improve the immunological response.5-8
Hepatitis B vaccination and antibodies control requires dedication, time, and follow-up from physicians and nurses. Epidemiological surveys present patients on dialysis not vaccinated or in which the antibody levels were not measured. In 1995, only 35% of the patients in the USA had received the vaccine.9-11
According to the protocol of 1989, we determined in the first annual control serological markers and anti-HBs antibodies and afterwards we strictly proceeded to vaccination.
In 2004, we began to measure the levels of anti-HBs antibodies every six months. In 2007, we had 31 patients on the protocol of 1989, and antibody controls every 6 months and every 12 months. We could observe the following findings:
Six patients (19.35%) did not respond in any control either to the first vaccination or revaccinations.
The remaining 25 patients (80.65%) had in at least one control anti-HBs antibodies higher than 10 mIU/mL. Controls at six months were not different to annual controls in 17 of these patients (54.8%).
In 8 patients of the group of responders (table I), the controls performed at 6 months yielded information not obtained in the annual determination. In 4 of these patients (12.9%) the antibodies had already decreased below the protective range and the patients could benefit from a revaccination 6 months before the annual control.
In 7 patients (22.5%), the controls at six months after revaccination showed protective levels of antibodies, but at the annual control they already were below 10 mIU/mL. These results led to consider the patients as non-responders. Moreover, 3 of the 7 patients never had protective antibody levels on annual controls. Had not the controls at 6 months be performed, they would have been considered as non-responders to vaccination.
Antibody controls every 6 months disclose some patients that respond to vaccination but would not be detected only on annual controls. Besides, they help identifying a group of patients in whom the antibody levels have already diminished below 10 mIU/mL and could benefit from a semestral vaccination protocol.
