Switching the default: Development and effectiveness of pre-booked appointments on COVID-19 vaccination uptake

Background: In autumn 2023, COVID-19 vaccination invitations in the Netherlands shifted from self-scheduling to pre-booked appointments for selected groups. While defaulting to pre-booked slots may increase uptake, potential rebound effects remain unclear. We examine preferences between appointment types, their effect on vaccination intentions, and whether effects are different for individuals hesitant about this vaccination round.Methods: A mixed-methods approach was used to assess vaccination intentions for three groups (<60 with influenza vaccination indication, 60-69 and 70+ years) eligible for pre-booked appointments. Study 1 examined attitudes around pre-booked appointments in 15 interviews. Study 2 experimentally tested preferences for pre-booked appointments vs self-scheduled appointments and their effect on vaccination intentions in a representative online panel (n=1.886) and those who experience hesitancy about this vaccination.Findings: Interviews showed that pre-booked appointments are seen as presumptuous or inconvenient (a potential indicator of reactance) by some, but also as a useful aid in support of vaccination uptake, sometimes by the same people. Participants in Study 2 indicated a preference for self-scheduling (Coefficient = -.23) but this preference did not translate to differences in vaccination intentions (Adjusted OR =1.11) Similar results were observed in the hesitant subgroup (Coefficient = –.25; Adjusted OR = 0.88).Discussion: In our study pre-booked appointments do not change COVID-19 vaccination intentions. As pre-booked appointments evoked negative and positive sentiments and self-scheduling was found easier and more pleasant, it is important to examine potential rebound effects of switching the default, particularly amongst subgroups in the population with lower intentions.