Table 3

Summary of nudging interventions derived from this systematic review

Type of nudgingRationaleNudging-based approaches employed in the included studies
Make available information salientPeople behave differently, depending on which information is salient in that particular moment.41Reminders (vaccinations due soon) and recalls (vaccinations past due) increase coverage across populations, vaccines and mode of delivery:
  1. use of personalised celebration card sent to parents/caregivers before their children’s vaccination schedule;46

  2. directly sending individualised letters (in a coloured banner with aboriginal artwork and highlighting the word ‘free’)47 or reminders via personalised letters, postcards or text message to increase vaccination uptake;47–52

  3. use of computer-based and phone-based software programs to generate automatic reminder text messages to parents;53 54

  4. use of an electronic health record-based decision support system for clinicians to receive an automated reminder to recommend initial or succeeding doses of vaccines to patients;55–57

  5. use of a familiar and trusted source (eg, own physician vs the national health system) to deliver vaccination reminders/recall;60 61

  6. use of improved screening tools and automatic provider notification or reminders;58

  7. use of an email prompt to spark vaccination intention among employees;59

  8. use of motivational interviewing phone calls to parents to address commonly asked questions about vaccine.48

An invitation that recommends getting an early shot to increase vaccine effectiveness.66
Emphasis on disease salience, disease threat and promotion of self-efficacy to increase intention to vaccinate via educational messages, videos or pamphlets among pregnant mothers and parents.62–65
Offer incentivesIncentives, both tangible and intangible, can increase favoured behaviour.41 42Offering incentives for vaccinations:
  1. giving vouchers for free or discounted vaccines to increase uptake;45 67 68

  2. offering parents 1 kg of raw legumes per immunisation schedule and a set of meal plates after completion of immunisation schedule.70

Offering incentives to promote return of vaccine consent forms among adolescents.69
Change defaultsChanging whether something is the default option versus requiring explicit opt-in can change behaviour.41 42Presenting parents with hypothetical options to opt in (vaccination would only occur if parents completed a form saying to) or to opt out (vaccination would occur unless parents completed a form saying not to) of vaccinations.73 74
In the doctor–patient interaction, switching to presumptive communication (eg, ‘Today we are vaccinating your child.’) from participatory communication (eg, ‘Will we do vaccinations today?’).71 72
Change the messengerChanging who delivers the message (eg, a trusted source or a peer) can alter how the message is received.41 43Training parental advocates on vaccination to address the issue in their peer group and community.75
Delivering provaccine messages by ordinary people as opposed to medical experts.44
Change the way outcomes are framedThe same outcome is perceived differently when communicated in terms of benefits gained (eg, lives saved) versus losses avoided (eg, deaths averted).41 43Framing vaccinations in terms of
  1. gain-framed messaging (describing benefits of receiving vaccines) versus loss-framed messaging (describing the cost of not receiving the vaccine);76 77 79–81

  2. vaccine benefits on an individual rather than societal level;44 78 82

  3. message order (from positive (vaccine effectiveness) to negative (vaccine side effects) or vice versa).83

Invoke social normsBeing aware of how others behave in a particular situation or feeling strongly about an issue can cause people to change their own behaviour.41 43Using a storytelling narrative video to tell the parents that their community members, friends and doctors think that they should be vaccinated.84
Using community campaigns and parent advocates to explicitly appeal to local values around social justice, parenting and alternative lifestyles.85
Featuring a celebrity to establish a social norm about vaccination.45
Encourage Emotional AffectThe use of emotional associations (words, images and events) affects behaviour.41Using visually enhanced education (images, videos, personal experiences and anecdotes) to elicit emotional connections to increase perception of vaccine effectiveness and comfort.86–88
Using dramatic narratives:
  1. featuring an infant who almost died of measles and displaying visuals or ‘disease images’91

  2. embedding narratives in radio programming to stimulate a more realistic experience.89

Graphical presentation of vaccine risk statistics accompanied by a rhetorical question such as ‘Do you want to protect your daughter? If there was a vaccine to protect your daughter against cancer, would you have her get it?’.90