Immune response to the hepatitis B virus vaccine in health care workers and its persistence.

ANDREA SALOMONE; NATALIA ALOISI; CARMEN STANGANELLI; CLAUDIA FERRARIO; GOLDSTEIN DE FINK SUSANA

Salvador, Bahia

Congreso; VIII Congresso Brasileiro de Biossegurança.; 2013

Associacao Brasileira de Biossegurança

Hepatitis B virus (HBV) is a usual cause of viral hepatitis with health complications that include cirrhosis and hepatocellular carcinoma. It is the major infectious hazard for healthcare and research workers. Currently available HBV vaccines, based on the recombinant surface virus antigen (HBs), confer protection to a high proportion of the vaccinated population. Antibody (Ab) titers are evaluated 30-60 days after the third dose. In general it is considered that individuals are protected when their Ab titer is above >10 mUI/mL. The risk of contracting HBV by health care workers (HCW) is four-times greater than that of general adult population, so a higher Ab titer for them to be fully covered is suggested (>100 mUI/mL). Countries differ in requiring or not booster shots. Many HCW have never been evaluated after immunization, so they are unaware of their vaccination status. The aim of this study was to evaluate the protection against HBV in HCWs that had completed a course of 3 vaccinations. Participants work at one of two institutions in the city of Buenos Aires and signed an informed consent. This study was approved by the ethics committees of both centers. Serum levels of anti-HBs Abs were evaluated by enzyme-linked immunoassay (anti-HBs, Radim, Italy) in 228 individuals. Participants were classified according to their Ab titers in three groups: G1: <10 mIU / mL, G2: 10-100 mUI/mL and G3: >100 mUI/mL. Of all cases 84.2% presented Abs> 10 mIU / mL (36% of G2, 48.2% of G3). Twenty percent (20.3%) of men are in G1 compared to 14.5% of women. We observed no difference in antibody levels for post-vaccination time <5 years vs.> 5 years, P> 0.05. In the literature a rate of 5-20% non-responders (NR) has been reported. In our case 15.8%are in G1 and they must be reassessed after a second course of vaccinations to be definitively classified or not as NR. On the other hand, some individuals with previous high Ab titersshowed decreased or lack of them. In order to determine if immunological memory was present in spite of the loss of Abs, a proliferation assay was set up; using the HBs as a stimulus, and evaluating incorporation of tritiated thymidine. Apparently there is a cellular immune response in those individuals with an initial positive Ab response to the vaccine, even though their Ab levels dropped over time. These preliminary results suggest that once they have a successful vaccination, even individuals from high risk groups such as HCWs remain protected against HBV infection.