The Hepatitis B Vaccine Protects Re-Exposed Health Care Workers, But Does Not Provide Sterilizing Immunity
Jens M. Werner
,
Adil Abdalla
,
Naveen Gara
,
Marc G. Ghany
,
Barbara Rehermannemail address
Immunology Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland
Liver Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland
Received 3 January 2013; accepted 23 July 2013. published online 02 August 2013.
Background & Aims
Infection with hepatitis B virus (HBV) can be prevented by vaccination with HB surface (HBs) antigen, which induces HBs-specific antibodies and T cells. However, the duration of vaccine-induced protective immunity is poorly defined for health care workers who were vaccinated as adults.
Methods
We investigated the immune mechanisms (antibody and T-cell responses) of long-term protection by the HBV vaccine in 90 health care workers with or without occupational exposure to HBV, 10−28 years after vaccination.
Results
Fifty-nine of 90 health care workers (65%) had levels of antibodies to HBs antigen above the cut-off (>12 mIU/mL) and 30 of 90 (33%) had HBs-specific T cells that produced interferon-gamma. Titers of antibodies to HBs antigen correlated with numbers of HBs-specific interferon-gamma−producing T cells, but not with time after vaccination. Although occupational exposure to HBV after vaccination did not induce antibodies to the HBV core protein (HBcore), the standard biomarker for HBV infection, CD4+ and CD8+ T cells against HBcore and polymerase antigens were detected. Similar numbers of HBcore- and polymerase-specific CD4+ and CD8+ T cells were detected in health care workers with occupational exposure to HBV and in patients who acquired immunity via HBV infection. Most of the HBcore- and polymerase-specific T cells were CD45RO+CCR7−CD127− effector memory cells in exposed health care workers and in patients with acquired immunity. In contrast, most of the vaccine-induced HBs-specific T cells were CD45RO−CCR7−CD127− terminally differentiated cells.
Conclusions
HBs antigen vaccine-induced immunity protects against future infection but does not provide sterilizing immunity, as evidenced by HBcore- and polymerase-specific CD8+ T cells in vaccinated health care workers with occupational exposure to HBV. The presence of HBcore- and HBV polymerase-specific T-cell responses is a more sensitive indicator of HBV exposure than detection of HBcore-specific antibodies.