Natural and induced immunity to hepatitis B virus among the staff of a pediatric oncology center

Abstract

All employees of St. Jude Children's Research Hospital who were at risk for occupational exposure to hepatitis B virus were considered appropriate candidates for immunization when the vaccine was licensed in November 1981. Because a high prevalence of hepatitis B immunity was expected among the staff, preimmunization screening was undertaken in the belief that it would be cost effective. Of 315 candidates screened for antibody to the hepatitis B surface antigen (anti-HBs), 79 (25%) had detectable levels and 48 (15%) had titers of ≥10 ratio units (RU). The highest rates of anti-HBs positivity were found among housekeepers (40%), nursing assistants (35%), physicians (31%), clinical laboratory workers (29%), and ward clerks (27%); nurses had the lowest rate (16%). An evaluation of potential risk factors implicated age >30 years as having greatest importance. Serum samples were collected from 221 employees 3 months after their third dose of vaccine and tested for anti-HBs; 218 (98.6%) were seropositive. Eighteen employees who had detectable anti-HBs in the range of 2.1 to 9.9 RU before immunization responded well to the vaccine; the titers rose from an average of 4 RU before vaccination to an average of 313 RU 3 months after the third dose. The findings indicate that preimmunization screening of all health care workers identified as candidates for vaccination may not be necessary or economically feasible. If a screening program is undertaken, however, anti-HBs testing of only those persons >30 years of age would increase the program's cost effectiveness.