Recent papers in the Bulletin show that communication is a complex social process, somewhat uncontrollable and dynamic, but one that contributes to health outcomes and fosters good governance in even the most difficult situations.1–3 The principles of evidence-based care can be used to inform efficient health communication on two counts. First, communication should have explicit aims. For example, polio eradication has shown that it is important to distinguish between different ways of accomplishing the same target. Do we want to increase general demand for vaccination, in which case we might select a public information campaign to let people know why vaccination is important?4 Or do we want to specifically make up for missed vaccinations? This could be done by reminding parents or by vaccinating children during clinic visits made for other reasons.5 Both strategies seek to increase vaccination rates, but tackle different problems, require different approaches and have different short-term goals. To meet explicit aims, interventions need to be planned and developed in a way that permits them to be sequenced, modified or adapted for different populations or situations. Communication interventions that have structured form and content are easier to describe and classify, which in turn aids evaluation and adaptation.6 While some situations – such as risk communication – call for adherence to a fairly rigid script, most cases require variations on the original protocol. Second, evidence-based care encourages us to be systematic and transparent in reporting processes and outcomes. This makes it easier to see gaps. A major gap in how we conceive communication strategies is the ‘directional gap’. Communication is often conceived as communication to members of the public, to patients, to health consumers, to informal caregivers. Communication comes from health professionals, governments, researchers, health companies, etc. However, understanding the agency, ideas, constraints and burdens that affect the recipients of health communication is critical to improving that communication between and among professionals, researchers, government and the public.7,8 Published research is one way to measure communication priorities and concerns. The Cochrane Consumers and Communication Review Group has analysed its trials register to assess and code the number of interventions in trials in six broad communication directions.9 The analysis was done using 6728 trials, with the caveat that complex interventions may be coded for more than one direction.10 Of these trials, over two-thirds studied interventions of communications to the consumer (such as instructions on taking medicines). Most of the remainder were trials that studied communications between health providers and consumers (such as decision aids). Relatively few trials studied communication from the consumer (such as patient reporting of self-monitoring), between consumers (such as self-help groups), or to the health-care provider from another source (such as communication training). Nevertheless, the existence of these trials in multidirectional communication provides and opportunity for evidence synthesis. Such a synthesis could establish whether public health strategies that enable consumers to communicate with each other are more effective than those that do not. A recent example is the United Kingdom’s online national pandemic flu service that helps people assess their symptoms and request antivirals.11 A visit to a general practitioner is not necessary and the affected individual is advised to select a ‘flu friend’ to pick up the medicine from a collection point. The difficulty of retaining one-way communications can be seen in the simultaneous responsibility that is heaped on the public; to keep up to date with screening, act to maintain health, know about medicines, recognize the latest risks, manage the family’s health, budget for health care and plan for end-of-life. There is so much to do that merely telling people what to do is not enough. Health communication strategies need to evolve accordingly. ■