Structuring our response to hospital outbreaks under conditions of uncertainty Michael R. Millar * Department of Infection, Royal London Hospital, Barts and the London NHS Trust, London, UK A RT I C L E I N F O Article history: Received 30 July 2013 Accepted 3 November 2013 Available online 1 December 2013 Keywords: Outbreaks Precautionary Uncertainty SUMM ARY Background: Sometimes decisions have to be made even when we do not have all of the information that we would like to have. It is not uncommon for infection control pro- fessionals to be faced with an outbreak of colonization or infection while there is un- certainty about the impact of the outbreak on patient outcomes. How do we decide a proportional response when we do not know the seriousness of the outbreak? Aim: The precautionary approach has become established in the European Union (EU) as a way of structuring responses to potentially serious threats (such as novel pandemic influenza viruses) when there are substantial uncertainties about the true impact of the threat. The potential of this approach to help with structuring responses to outbreaks involving substantial uncertainties is considered in this article. Methods: The EU approach requires that actions should be proportional, non- discriminatory, consistent, take account of costs and benefits, be subject to review, and that the responsibility for producing the scientific evidence to fill critical information gaps is assigned. The example of management of outbreaks with multidrug-resistant Acineto- bacter baumannii is used here to illustrate how the precautionary approach might be used in infection prevention and control. Findings and conclusion: The precautionary approach has potential to provide a struc- tured response to outbreaks of hospital infection when there is uncertainty about the impact of the outbreak on outcomes. Most importantly there is a requirement that we specify which risks we are prioritizing for control, the information that is uncertain but critical to informing decisions, and the responsibilities for gathering that information. ª 2013 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved. Introduction A recent report from the charity Sense about Science was entitled Making sense of uncertainty. 1 The main emphasis of the report was on the importance of acknowledging the inevitability of uncertainty in science. Infection control professionals are frequently confronted with having to take action without having all of the information that they would like to have. Lipsitch et al. capture this quandary when they state that: Early action is required, but decisions about action must be made when the threat is only modest e and consequently, they involve a trade-off between the comparatively small, but nearly certain, harm that an intervention may cause (such as rare adverse events from large-scale vaccination or economic and social costs from school dismissals) and the uncertain probability of much greater harm from a widespread outbreak. This combination of urgency, uncertainty, and the costs of interventions makes the effort to control infectious diseases especially difficult. 2 * Address: Department of Infection, Level 3, Pathology and Pharmacy Building, Royal London Hospital, 80 Newark Street, Whitechapel, London E1 2ES, UK. Tel.: þ44 (0) 203 2460296; fax: þ44 (0) 203 2460303. E-mail address: Michael.Millar@bartshealth.nhs.uk. Available online at www.sciencedirect.com Journal of Hospital Infection journal homepage: www.elsevierhealth.com/journals/jhin 0195-6701/$ e see front matter ª 2013 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jhin.2013.11.006 Journal of Hospital Infection 86 (2014) 90e94