Communicable E58: Reducing hospital-acquired pneumonia – the HAPPEN trial and how it happened

In this episode of *Communicable*, Angela Huttner and Josh Davis are joined by Brett Mitchell, Aline Wolfensberger and Lauren Clack to discuss the HAPPEN trial to prevent hospital-acquired pneumonia led by Mitchell--and the important studies leading up to it \[1-3]. The episode also explores trial designs used in their research that are both creative and practical, such as stepped-wedge and implementation trials, and how these approaches can bridge the gap between research and real-world practice. References 1. Mitchell B, “The hospital acquired pneumonia prevention (HAPPEN) study: a multi-centre randomised controlled trial” in ESCMID Global 2026. https://online.escmid.org/media-6348-hospital-and-ventilator-associated-pneumonia-new-insights-on-prevention-diagnosis-and-treatment (Presentation). 2. White NM, et al. Effectiveness of oral care for the prevention of non-ventilator hospital-acquired pneumonia (HAPPEN): a multicentre, stepped-wedge, cluster-randomised trial in Australia. *Lancet Infect Dis* 2026. DOI: 10.1016/S1473-3099(26)00235-5. 3. Wolfensberger A, et al. Prevention of non-ventilator-associated hospital-acquired pneumonia in Switzerland: a type 2 hybrid effectiveness–implementation trial. *Lancet Infect Dis* 2023. DOI: 10.1016/S1473-3099(22)00812-X. Further reading - Cassini A, et al. Burden of Six Healthcare-Associated Infections on European Population Health: Estimating Incidence-Based Disability-Adjusted Life Years through a Population Prevalence-Based Modelling Study. *PLoS Med* 2016. DOI:  10.1371/journal.pmed.1002150. - Pronovost P, et al. An Intervention to Decrease Catheter-Related Bloodstream Infections in the ICU. *NEJM*. DOI: 10.1056/NEJMoa061115. - Bion J, et al. ‘Matching Michigan’: a 2-year stepped interventional programme to minimise central venous catheter-blood stream infections in intensive care units in England. *BMJ Quality & Safety* 2013. DOI: 10.1136/bmjqs-2012-001325. - Dixon-Woods M, et al. Explaining Matching Michigan: an ethnographic study of a patient safety program. *Implementation Sci* 2013. DOI: 10.1186/1748-5908-8-70. - Clack L, et al. Hybrid effectiveness-implementation studies in infection prevention and infectious diseases: a narrative review. *CMI* 2025. DOI: 10.1016/j.cmi.2025.10.022.