Investigating Bordetella pertussis colonisation and immunity: protocol for an inpatient controlled human infection model

Abstract

Introduction: We summarise an ethically approved protocol for the development of an experimental human challenge colonisation model. Globally Bordetella pertussis is one of the leading causes of vaccine-preventable death. Many countries have replaced whole cell vaccines with acellular vaccines over the last 20 years during which pertussis appears to be resurgent in a number of countries in the developed world that boast high immunisation coverage. The acellular vaccine provides relatively short-lived immunity and, in contrast to whole cell vaccines, may be less effective against colonisation and subsequent transmission. To improve vaccine strategies, a greater understanding of human B. pertussis colonisation is required. This article summarises a protocol and does not contain any results.

Methods and analysis: A controlled human colonisation model will be developed over two phases. In phase A, a low dose of the inoculum will be given intranasally to healthy participants. This dose will be escalated or de-escalated until colonisation is achieved in approximately 70% (95% CI 47% to 93%) of the exposed volunteers without causing disease. The colonisation period, shedding and exploratory immunology will be assessed during a 17-day inpatient stay and follow-up over 1 year. The dose of inoculum that achieves 70% colonisation will then be confirmed in phase B, comparing healthy participants exposed to B. pertussis with a control group receiving a sham inoculum.

Ethics and dissemination: This study has been approved by the ethical committee reference: 17/SC/0006, 24 February 2017. Findings will be published in peer-reviewed open access journals as soon as possible.

Keywords: bordetella pertussis; colonisation; human challenge study; vaccine development; whooping cough.

Figure 1

Escalating or de-escalating the dose of the inoculum according to colonisation frequency.

Figure 2

Visits and admission design.

Figure 3

Actions to be taken when symptoms of early Bordetella pertussis disease are suspected. CRP, C reactive protein; PI, principal investigator; URTI, upper respiratory tract infection; WCC, white cell count.