Global validation of 12 behavioural strategies
| Behavioural strategy* | Definition | Phase | Mechanism type | Global validation, % | Variance in global adaptation | Efficacy versus US (sig <0.05) |
| Identity segments | Attitude towards vaccine is influenced by a person’s self-identity or membership in a group. Target messages towards different identities and use group leaders or celebrities. | 2 | Social mechanism: affiliation/affect | 83.3 | High | Similar |
| Common enemy | Unite highly polarised groups by framing vaccination as defeating a common enemy that both strongly dislike. | 3 | Social mechanism: affiliation/affect | 82.4 | High | Similar |
| Analogy | Explain processes (how the vaccine works) and risks (the odds of getting sick) with accurate analogies. | 1 | Cognitive mechanism: net benefits | 94.2 | Moderate | More |
| Observability | Make vaccinated persons a walking advertisement for vaccine popularity by making the # of vaccinated observable. | 2 | Social mechanism: affiliation/affect | 87.2 | Minimal | More |
| Leverage scarcity | Use the natural scarcity of the vaccine to frame it as highly precious. | 1 | Cognitive mechanism: implicit nudge | 83.5 | High | Similar |
| Negative attributions | Monitor and directly address incorrect negative attributions made about the vaccine or its delivery. | 1 | Cognitive mechanism: net benefits | 92.9 | Minimal | More |
| Anticipated regret | Ask people to consider what would happen and how they would feel if they or someone they loved were to get sick. | 3 | Social mechanism: affiliation/affect | 84.9 | High | More |
| Piecemeal risk info | Be aware that people see greater risk when information trickles out over time and thus changing info about vaccine roll-out may logically increase anxiety. | 3 | Cognitive mechanism: net benefits | 84.7 | Minimal | Similar |
| Compromise effect | When uncertain, people feel more confident about compromise options, so frame their vaccination ‘choice’ as the middle of three options. | 2 | Cognitive mechanism: implicit nudge | 74.7 | High | Similar |
| FOMO incentives | Trigger loss aversion by mentioning incentives that people may miss out on by not vaccinating now. | 2 | Social mechanism: affiliation/affect | 85.2 | Moderate | Similar |
| Uniqueness neglect | Look for hesitant people who see the vaccine as a ‘one-size-fits-all’ solution but see themselves as ‘not average’ and offer small special accommodations to them. | 3 | Cognitive mechanism: implicit nudge | 73.8 | High | Less |
| Base-rate fallacy | People are more persuaded by stories than statistics, so counter a hesitant person’s fear of unlikely bad outcomes with positive stories first and statistics second (if at all). | 1 | Cognitive mechanism: net benefits | 96.5 | Minimal | More |
*Behavioural strategies as described previously. (1) Promotion phase suggests when the strategy may be most effective. Phase 1: strategies that build understanding of a vaccine’s net benefits and are considered for early communication. Phase 2: strategies that prompt follow-through are considered for communication around vaccination campaigns. Phase 3: those that address populations that remain resistant. Mechanism is categorisation based on the underlying psychological mechanism of the strategy. Global validation is the proportion of the panel that responded yes or maybe to question of ‘whether the strategy would be helpful in your region.’ Variance in global adaptation reflects the diversity observed in recommendations of the Delphi Panel for local adaptation (as observed in open-ended responses). Efficacy compared with USA is rating (seven-point semantic differential scale item where 1=less, 7=more than USA); one sample t-test compared with midpoint).
†
FOMO, fear of missing out.