A Comparison of Two Strategies to Prevent Pertussis in Vaccinated Healthcare Personnel Following Pertussis Exposure

Background: � Until the licensure of an effective acellular pertussis vaccine (Tdap) for use in adults in 2005, antibiotic post-exposure prophylaxis was the only method to reduce acquisition of pertussis by healthcare personnel following a pertussis exposure.� In 2006 the Centers for Disease Control and Prevention recommended healthcare personnel with direct patient contact receive a single booster dose of Tdap to reduce nosocomial spread of pertussis.� Pertussis vaccination may eliminate the need to provide antibiotic post-exposure prophylaxis in recently-vaccinated healthcare personnel.�

Objective: � To determine if close symptom monitoring following a pertussis exposure of Tdap-vaccinated healthcare personnel is non-inferior to routine antibiotic post-exposure prophylaxis.

Methods: Personnel with direct patient contact at a tertiary care 206-bed pediatric hospital were vaccinated with Tdap.� Personnel subsequently exposed to an index patient with pertussis were randomly assigned to receive standard antibiotic prophylaxis or no prophylaxis following the exposure.� Nasopharyngeal and serum specimens were obtained at baseline upon identification of the exposure and 21 days later.� Nasopharyngeal specimens were tested for Bordetella pertussis via polymerase chain reaction (PCR), while serum specimens were tested for anti-pertussis toxin (PT) antibodies.� Subjects in both arms were queried daily for symptoms, and an additional nasopharyngeal specimen was collected in symptomatic subjects for PCR and culture testing.� The primary outcome was laboratory-confirmed pertussis defined as a positive nasopharyngeal specimen (by either culture or PCR), a two-fold rise in anti-PT titers, or a single anti-PT titer of ≥94 EU/mL.� Close symptom monitoring without antibiotic prophylaxis was considered non-inferior to antibiotic post-exposure prophylaxis if the lower limit of the one-sided 95% confidence interval (CI) for the reduction in pertussis infection was greater than -7%.

Results: Between May 21, 2007, and October 8, 2009, 1,091 pediatric healthcare personnel were vaccinated with Tdap.� Eighty personnel were exposed a total of 94 times.� Twenty-four personnel were not eligible for randomization.� Thirty-four personnel were randomly assigned to receive azithromycin prophylaxis, and 36 received no prophylaxis.� Pertussis infection occurred following a healthcare exposure in 6 persons (16.7%) in the group without prophylaxis and 1 person (2.9%) in the antibiotic prophylaxis group (absolute risk difference -13.7%; lower bound of the one-sided 95% CI, -25.0%; p=0.06).

Conclusions: � Close symptom monitoring of healthcare personnel following a pertussis exposure did not meet the criteria for noninferiority.� However, the low rate of symptomatic pertussis in both groups warrants further study of this approach.