“…Prior research suggests that offering such reflections can also improve the effects of nudges (Mühlböck et al, 2022;Banerjee et al, 2022;Keppeler et al, 2022). Building on studies testing the effects of nudges on vaccination uptake (Keppeler et al, 2022;Serra-Garcia and Szech, 2022;Tentori et al, 2022;Milkman et al, 2011Milkman et al, , 2021Milkman et al, , 2022Dai et al, 2021;Patel, 2021), we extend research on "nudge+" approaches to evaluate its effects at promoting booster vaccine uptake intentions during the COVID-19 pandemic.…”