Table 1

Global validation of 12 behavioural strategies

Behavioural strategy*DefinitionPhaseMechanism typeGlobal
validation, %
in global adaptation
Efficacy versus US
(sig <0.05)
Identity segmentsAttitude 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.2Social mechanism: affiliation/affect83.3HighSimilar
Common enemyUnite highly polarised groups by framing vaccination as defeating a common enemy that both strongly dislike.3Social mechanism: affiliation/affect82.4HighSimilar
AnalogyExplain processes (how the vaccine works) and risks (the odds of getting sick) with accurate analogies.1Cognitive mechanism: net benefits94.2ModerateMore
ObservabilityMake vaccinated persons a walking advertisement for vaccine popularity by making the # of vaccinated observable.2Social mechanism: affiliation/affect87.2MinimalMore
Leverage scarcityUse the natural scarcity of the vaccine to frame it as highly precious.1Cognitive mechanism: implicit nudge83.5HighSimilar
Negative attributionsMonitor and directly address incorrect negative attributions made about the vaccine or its delivery.1Cognitive mechanism: net benefits92.9MinimalMore
Anticipated regretAsk people to consider what would happen and how they would feel if they or someone they loved were to get sick.3Social mechanism: affiliation/affect84.9HighMore
Piecemeal risk infoBe aware that people see greater risk when information trickles out over time and thus changing info about vaccine roll-out may logically increase anxiety.3Cognitive mechanism: net benefits84.7MinimalSimilar
Compromise effectWhen uncertain, people feel more confident about compromise options, so frame their vaccination ‘choice’ as the middle of three options.2Cognitive mechanism: implicit nudge74.7HighSimilar
FOMO incentivesTrigger loss aversion by mentioning incentives that people may miss out on by not vaccinating now.2Social mechanism: affiliation/affect85.2ModerateSimilar
Uniqueness neglectLook 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.3Cognitive mechanism: implicit nudge73.8HighLess
Base-rate fallacyPeople 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).1Cognitive mechanism: net benefits96.5MinimalMore
  • *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.