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

• HAPPEN study website: Study overview and resources www.happenstudy.com
• 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.
• Hospital Acquired Pneumonia Prevention (HAPPEN) Study: Statistical Analysis Plan
  https://www.medrxiv.org/content/10.1101/2025.08.14.25333719v1
• Oral care practices and hospital-acquired pneumonia prevention: A national survey of Australian nurses
  https://pubmed.ncbi.nlm.nih.gov/38724299/
• Nurses' experiences of providing oral care to hospitalised patients: A qualitative study
  https://pubmed.ncbi.nlm.nih.gov/40450434/