Social media plays an increasingly important role in public health communication. It allows public health organisations to reach large numbers of people rapidly, in order to influence their health related knowledge, attitudes, intentions, and possibly their behaviours. During the covid-19 pandemic, for example, social media campaigns increased millions of people’s motivation to engage in protective behaviours and helped to increase vaccine uptake.12 Social media public health messaging could be enhanced by wider and better use of behavioural sciences.

There is a growing body of literature showing that behavioural science theories and frameworks can enhance the effectiveness of health interventions, although behavioural science is still underused in public health.3 Social media public health messaging is often based on industry best practice or simply “trial and error” approaches; intentionally and systematically building behavioural science theories and frameworks into the design, implementation, and evaluation of public health social media communication activities would improve their rigour and effectiveness.4

Research looking at traditional public health communication—such as mass media print campaigns—has found that using behavioural science theories and frameworks can enhance their effectiveness.45 More research on social media behavioural interventions is needed to evaluate the extent to which academic research can be replicated in real world settings, including organic social media campaigns by public health groups.67

Applying behavioural science theories and frameworks can help make sense of how social media interventions work. For example, some health psychology theories, such as protection motivation theory, suggest that people’s beliefs about their self-efficacy, and the extent to which they perceive barriers or benefits, can affect whether they engage in any given behaviour.8 It also suggests that the perception of risk—that is, how susceptible we feel and how serious we feel the risk is—is a key predictor of how likely we are to engage in health protecting behaviours.

Message framing9 can help public health practitioners to create more impactful social media campaign messages. It can, for example, help to determine whether the way in which a message is framed—for example, in terms of a loss (what one stands to lose by not engaging in a healthy behaviour or engaging in a risky behaviour) or a gain (emphasising what one stands to gain by engaging in a healthy behaviour or by avoiding a risky behaviour) —can have different effects on the audience’s attitudes and possibly their intentionss.9 A recent study of covid-19 protective behaviours, such as physical distancing, hand washing, and mask wearing, found that although loss framed messages were more effective in increasing the perceived risk of covid-19, gain framed messages were more effective in increasing intentions to adopt the behaviours.10

Public health organisations can apply lessons from academic studies to implement behavioural science informed interventions in online public health campaigns. For example, an analysis of 71 World Health Organization online global campaigns on covid-19, viewed 13 million times, found that gain framed messages tended to perform better than loss framed messages for promoting behaviours including mask wearing and vaccination.11

Behavioural science methods can also help to conduct evaluations of social media campaigns. Although traditional metrics like engagement statistics are useful, it is hard to draw any insights or causal inferences as to whether that message made people think or act differently. We can’t determine if they perceive a greater risk or if their intentions to take action to reduce the risk increased or decreased. Using randomised online experiments to evaluate social media campaigns can help measure, through social media polls, any causal impact of messages on people’s perceptions, attitudes, and intentions around various health topics.2

A growing body of literature shows the importance and impact of an integrated behavioural insights approach into social media communications, including from WHO and other academic institutions and health organizations. A recent collaboration by Unicef and Yale University explored the impacts of different types of messaging, such as comparing “emotional” messaging with informational messaging on childhood immunisations. It found that emotional messaging was more memorable.12 Although, the linkage between emotional resonance and behavioural change may need further research. WHO has also run over 122 randomised field experiments implemented across online social media platforms since 2020. The associated campaigns reached hundreds of millions of people and helped to increase knowledge of health risk reducing behaviours.1

Both social media13 and behavioural science1 provide opportunities for improving the health of the public. By harnessing them to continue to build an evidence base of theory of informed and rigorously evaluated interventions in real world social media settings, we could improve the effectiveness of social media public health messaging.