eprintid: 10203396 rev_number: 7 eprint_status: archive userid: 699 dir: disk0/10/20/33/96 datestamp: 2025-01-15 14:30:58 lastmod: 2025-01-15 14:30:58 status_changed: 2025-01-15 14:30:58 type: article metadata_visibility: show sword_depositor: 699 creators_name: Grimani, Aikaterini creators_name: Stoffel, Sandro T creators_name: von Wagner, Christian creators_name: Sniehotta, Falko F creators_name: Vlaev, Ivo title: Using an inferior decoy alternative to nudge COVID-19 vaccination ispublished: pub divisions: UCL divisions: B02 divisions: D12 divisions: J96 keywords: Asymmetric dominance effect, Behavioural public policy, COVID-19, Decision making, Decoy effect, Nudge, Vaccination hesitancy, Humans, Male, Female, Adult, Adolescent, Young Adult, Vaccination, COVID-19, COVID-19 Vaccines, Intention, England, SARS-CoV-2 note: Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/. abstract: Optimizing vaccine uptake is a public health challenge that requires the implementation of effective strategies. The asymmetric dominance (or decoy) effect describes the increasing likelihood of selecting an option when a clearly inferior alternative is offered. Therefore, we aimed to test the impact of offering decoy alternatives-less convenient vaccination appointments-on vaccination intentions. Participants aged 18-33 years, residing in England, and initially not intending to get vaccinated, completed three online experiments. Participants were randomly assigned to either a control or an experimental condition in each experiment. The asymmetrically dominated options were: an appointment in two weeks at a distant location (experiment 1); a later time at the participant's local GP, pharmacy, or community centre (experiment 2); and a later time at a distant location (experiment 3). The primary outcome was vaccination intention, while secondary outcomes included an active interest in reading additional information about the vaccination procedure, perceived difficulty and cognitive effort. Initial analysis revealed no evidence of an asymmetric dominance effect. However, further subgroup analysis, supported by formative research, indicated that ensuring decoy alternatives are clearly perceived as inferior could enhance the effectiveness of this approach for certain individuals. date: 2025-01-11 date_type: published publisher: Springer Science and Business Media LLC official_url: https://doi.org/10.1038/s41598-024-84853-8 oa_status: green full_text_type: pub language: eng primo: open primo_central: open_green verified: verified_manual elements_id: 2352676 doi: 10.1038/s41598-024-84853-8 pii: 10.1038/s41598-024-84853-8 lyricists_name: Stoffel, Sandro lyricists_id: STSTO43 actors_name: Stoffel, Sandro actors_id: STSTO43 actors_role: owner funding_acknowledgements: PR-PRU1217-20501 [National Institute for Health Research (NIHR)]; PR-PRU1217-20501 [National Institute for Health Research (NIHR)]; PR-PRU1217-20501 [National Institute for Health Research (NIHR)] full_text_status: public publication: Scientific Reports volume: 15 number: 1 article_number: 1672 event_location: England issn: 2045-2322 citation: Grimani, Aikaterini; Stoffel, Sandro T; von Wagner, Christian; Sniehotta, Falko F; Vlaev, Ivo; (2025) Using an inferior decoy alternative to nudge COVID-19 vaccination. Scientific Reports , 15 (1) , Article 1672. 10.1038/s41598-024-84853-8 <https://doi.org/10.1038/s41598-024-84853-8>. Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/10203396/1/Grimani_et_at-2025-SR.pdf