Overcoming the COVID-19 pandemic requires motivating the vast majority of Americans to get vaccinated. However, vaccination rates have become politically polarized, and a substantial proportion of Republicans have remained vaccine hesitant for months. Here, we explore how endorsements by party elites affect Republicans’ COVID-19 vaccination intentions and attitudes. In a preregistered survey experiment (n = 1,480), we varied whether self-identified Republicans saw endorsements of the vaccine from prominent Republicans (including video of a speech by former President Donald Trump), from the Democratic Party (including video of a speech by President Joseph Biden), or a neutral control condition including no endorsements. Unvaccinated Republicans who were exposed to the Republican elite endorsement reported 7.0% higher vaccination intentions than those who viewed the Democratic elite endorsement and 5.7% higher than those in the neutral control condition. These effects were statistically mediated by participants’ reports of how much they thought Republican politicians would want them to get vaccinated. We also found evidence of backlash effects against Democratic elites: Republicans who viewed the Democratic elite endorsement reported they would be significantly less likely to encourage others to vaccinate and had more negative attitudes toward the vaccine, compared with those who viewed the Republican elite endorsement or the neutral control. These results demonstrate the relative advantage of cues from Republican elites—and the risks of messaging from Democrats currently in power—for promoting vaccination among the largest vaccine-hesitant subgroup in the United States.

克服 COVID-19 大流行需要激励绝大多数美国人接种疫苗。然而，疫苗接种率在政治上已经两极分化，相当一部分共和党人几个月来一直对疫苗犹豫不决。在这里，我们探讨了政党精英的认可如何影响共和党人的 COVID-19 疫苗接种意图和态度。在预先注册的调查实验中（n= 1,480），我们改变了自我认同的共和党人是否看到知名共和党人（包括前总统唐纳德特朗普的演讲视频）、民主党（包括约瑟夫拜登总统的演讲视频）或中性控制条件，包括无背书。接触到共和党精英代言的未接种疫苗的共和党人报告的疫苗接种意愿比看到民主党精英代言的人高 7.0%，比处于中立控制条件的人高 5.7%。这些影响在统计上通过参与者报告他们认为共和党政客希望他们接种疫苗的程度来调节。我们还发现了针对民主党精英的反弹效应的证据：看到民主党精英支持的共和党人报告说，与那些看到共和党精英支持或中立控制的人相比，他们鼓励他人接种疫苗的可能性要小得多，对疫苗的态度也更消极。这些结果证明了来自共和党精英的线索的相对优势——以及来自当前执政的民主党信息的风险——在美国最大的对疫苗犹豫不决的亚群中促进疫苗接种。