**3. Health campaigns in crisis situations**

Effective risk communication is a requirement in case of health emergencies and crises [2] and can assist the public in managing the crisis [36]. Health crises, including epidemics and pandemics, do not present an exception to this trend. For this reason, governments throughout the world heavily depend on health campaigns, described as "a systematic effort to change health behaviors (or attitudes and beliefs about health and/or social and environmental conditions that mediate health behaviors) within a target population of people who are at risk for a health problem or problems" [37]. Health messages by the government are also known as Public Service Announcements (PSAs, [38]). Contrary to traditional advertising messages, these materials set out to change individual behaviors. For this reason, they have been commonly used in health crises [39].

With PSAs appealing to individuals to change their behaviors and instructing them on how to achieve these proposed behavioral changes, they are in line with health campaigns' three communicative objectives: awareness, instruction or persuasion [37, 40]. In case of a health crisis, health campaigns primarily intend to raise awareness for the severity of the threat amongst the affected population and offer instruction to individuals on how to utilize self-protective measures [41, 42]. As such, PSAs appeal to individuals' self-efficacy [16, 43, 44]. For instance, health messages spread during the H1N1 influenza emphasized the need to take up hygiene measures, such as "hand washing, sanitizer use, covering of coughs and sneezes, and staying at home" ([16]: p. 5). Similar message content was also employed as part of national COVID-19 health campaigns.

Albeit different campaign themes exist, amongst them community building [16], messages typically center on risk reduction strategies [5, 30]. Particularly during health emergencies, information on which preventive measures should be taken is valuable [45]. These measures, for instance, could be nonpharmaceutical interventions (NPIs), which are nation-wide actions proposed by the government to resolve the health crisis [31]. NPIs are useful in controlling the pandemic and are, thus, often labeled "community mitigation strategies". With measures often concerning "disruptive actions" ([44], p. S2), individuals are forced to reconfigure their daily lives and routines [46]. For this reason, health risk messages must be carefully designed to prevent controversial arguments and negative emotions from surfacing [19, 47, 48].

Campaigns advocating NPIs rely on media messages to reach diverse publics in crisis situations [49]. While an increasing amount of research is available on how health messages are used to create awareness amongst the population during risk situations [33, 50–53]. In this chapter we review articles pertaining to health risk message design and focus on the special case of pandemics and emerging infectious diseases [8].
