Duration of Pertussis Immunity in Adults: a study of Healthcare Workers.

The aim of this study is to assess antibody persistence and cell-mediated immunity post administration of combined diphtheria-tetanus-acellular pertussis vaccine, Boostrix 'Trademark' (dTpa) in healthy adults who have received adult formulation diphtheria-tetanus-pertussis boosters 5-10 previously, compared to those that have not received a pertussis containing vaccine since childhood (<15 years of age). Health care workers (HCWs) in paediatric hospitals have been recommended to receive pertussis booster immunisations (Australian Immunisation Handbook 2013) as they are both at increased exposure to pertussis in the hospital and can cause nosocomial transmission to their patients. A booster dTpa immunisation (Boostrix™) is approved for use in Australia by the Therapeutic Goods Administration (TGA). It is now almost 10 years since Boostrix™ was introduced into Western Australia (2004) with high uptake by employees at Princess Margaret Hospital for Children in Perth and health care workers are being offered revaccination. Little is known about the duration of pertussis immunity in adults. No studies have yet provided an in-depth analysis of the immune responses induced by acellular pertussis vaccines and how fast these may wane over time. This study is a non-randomised cohort study. We propose to recruit a total of 150 healthy adults aged 23-64 years employed in the Child and Adolescent Health Service, University of WA School of Paediatrics and/or Telethon Kids Institute. Participants will be asked to attend 4 clinic visits over a 12 month period. These visits will take place at the Clinical Child Research Facility at Princess Margaret Hospital. Participants will be allocated to one of 2 groups depending upon whether or not they have previously received a booster for pertussis. During the first visit participants will be asked about their medical history, demographic data and previous reactions to vaccinations. Immunisation histories will be confirmed (if required) through hospital and GP records. In addition a brief medical directed medical examination may be conducted and vital signs will be taken. Females of child bearing potential will need to do a urine pregnancy test prior to vaccination. A blood sample of 25-30mls will be taken by trained staff before participants are vaccinated with Boostrix™. Following this, a 7 day diary documenting local reactions and adverse events will need to be completed. Further blood tests of 25-30mls will be taken 1 week, 4 weeks and 1 year post-vaccination. Safety data will be collected at each of these visits.