We study the impact of a novel COVID-19 vaccine mandate, targeting graduating high-school students, on first vaccine uptake. In 2021, the State Government of Western Australia (WA) required attendees at "Leavers" -- a large-scale state-supported graduation party held annually in November in a WA regional town -- to be vaccinated. Using administrative data that link date-of-birth (at the month level), school attendance, and first-dose vaccination records, we exploit the strict school-age laws in WA to run regression discontinuity designs (RDDs). In other words, we use the date-of-birth cutoff for starting compulsory schooling in WA to build the counterfactual vaccination outcomes for Year-12 (i.e. graduating) students. We run both static and dynamic RDDs, the latter consisting of daily RDD estimations in a one-year window centred around the policy deadline in November 2021. We find that the "Leavers mandate" -- which excluded unvaccinated Year-12 students from popular post-graduation events -- raised vaccination rates by 9.3 percentage points at the mandate deadline. The dynamic RDD estimates show that this effect is entirely due to pulling forward future vaccinations by 46-80 days, with no net increase in ultimate uptake. Our paper is first to disentangle "pull-forward" (intensive margin) versus "net" (extensive margin) effects of a vaccine mandate in a pandemic context -- meaning that we identify how much the mandate made eventually-vaccinated people anticipate their vaccination, and how much it induced vaccinations that would not have happened absent the mandate. We also bring new evidence on the efficacy of time-limited non-monetary incentives for accelerating vaccination campaigns. Keywords: mandate; vaccination; incentives; uptake; adolescents; timing; coverage. JEL: I12; I18.

翻译：本研究考察了一项针对高中毕业生的新型COVID-19疫苗强制令对首剂疫苗接种率的影响。2021年，西澳大利亚州政府要求参加"毕业狂欢节"（每年11月在西澳地区城镇举办的大规模州政府支持的毕业庆祝活动）的人员必须完成疫苗接种。通过整合出生月份数据、在校记录与首剂疫苗接种记录的行政数据，我们利用西澳严格的入学年龄法规实施断点回归设计。具体而言，我们以西澳义务教育入学年龄的出生日期截止点为工具变量，构建十二年级（即毕业班）学生的反事实疫苗接种结果。我们同时采用静态与动态断点回归方法，其中动态设计以2021年11月政策截止日为中心，在一年时间窗口内进行逐日断点回归估计。研究发现，"毕业狂欢节强制令"（该政策禁止未接种疫苗的十二年级学生参加热门毕业活动）使政策截止日的疫苗接种率提升9.3个百分点。动态断点回归估计表明，该效果完全源于将未来46-80天的疫苗接种行为提前实现，并未产生最终的净增长效应。本文首次在大流行病背景下分离了疫苗强制令的"拉动效应"（集约边际）与"净效应"（广延边际）——即量化了强制令促使最终接种者提前接种的程度，以及在没有强制令情况下本不会发生的接种数量。本研究还为时限性非货币激励措施在加速疫苗接种运动中的有效性提供了新证据。关键词：强制令；疫苗接种；激励机制；接种率；青少年；时机选择；覆盖率。JEL分类号：I12；I18。