The Hepatitis B virus (HBV), which attacks the liver and is commonly transmitted by blood or blood-derived body fluids, is highly infectious and can be fatal; however, people who receive the proper vaccination before being exposed to HBV are protected from the disease. Those who begin receiving the vaccination series within a week of being exposed to HBV do not get the disease 75 percent of the time. The OSHA regulations require the screening pretest for HBV antibodies to identify previously infected persons who do not need to be vaccinated. The identification of carriers enables an agency to institute control procedures to protect coworkers, families, and the public from infection. Those who develop antibodies to the HBV through vaccination prior to exposure are protected from the disease. The OSHA ruling will require affected employers to begin offering the shots within 180 days after the final rule is published in the Federal Register.