Encouraging routine COVID-19 vaccinations is likely to be a crucial policy challenge for decades to come. To avert hundreds of thousands of unnecessary hospitalizations and deaths, adoption will need to be higher than it was in the autumn of 2022 or 2023, when less than one-fifth of Americans received booster vaccines^1,2. One approach to encouraging vaccination is to eliminate the friction of transportation hurdles. Previous research has shown that friction can hinder follow-through³ and that individuals who live farther from COVID-19 vaccination sites are less likely to get vaccinated⁴. However, the value of providing free round-trip transportation to vaccination sites is unknown. Here we show that offering people free round-trip Lyft rides to pharmacies has no benefit over and above sending them behaviourally informed text messages reminding them to get vaccinated. We determined this by running a megastudy with millions of CVS Pharmacy patients in the United States testing the effects of (1) free round-trip Lyft rides to CVS Pharmacies for vaccination appointments and (2) seven different sets of behaviourally informed vaccine reminder messages. Our results suggest that offering previously vaccinated individuals free rides to vaccination sites is not a good investment in the United States, contrary to the high expectations of both expert and lay forecasters. Instead, people in the United States should be sent behaviourally informed COVID-19 vaccination reminders, which increased the 30-day COVID-19 booster uptake by 21% (1.05 percentage points) and spilled over to increase 30-day influenza vaccinations by 8% (0.34 percentage points) in our megastudy. More rigorous testing of interventions to promote vaccination is needed to ensure that evidence-based solutions are deployed widely and that ineffective but intuitively appealing tools are discontinued.

鼓励常规 COVID-19 疫苗接种可能是未来几十年的一项关键政策挑战。为了避免数十万人不必要的住院和死亡，采用率需要高于 2022 年秋季或 2023 年，当时只有不到五分之一的美国人接种了加强疫苗^1,2 。鼓励疫苗接种的一种方法是消除交通障碍的摩擦。先前的研究表明，摩擦可能会阻碍后续行动³ ，并且居住地距离 COVID-19 疫苗接种点较远的个人接种疫苗的可能性较小⁴ 。然而，提供前往疫苗接种地点的免费往返交通的价值尚不清楚。在这里，我们表明，为人们提供免费往返药店的 Lyft 乘车服务除了向他们发送行为信息短信提醒他们接种疫苗之外没有任何好处。我们通过对美国数百万 CVS 药房患者进行一项大型研究来确定这一点，测试了 (1) 免费往返 Lyft 乘车前往 CVS 药房进行疫苗接种预约和 (2) 七组不同的行为告知疫苗提醒消息的效果。我们的结果表明，在美国，为之前接种过疫苗的个人免费提供前往疫苗接种点的服务并不是一项好的投资，这与专家和非专业预测者的高期望相反。相反，应该向美国人发送行为知情的 COVID-19 疫苗接种提醒，这使 30 天的 COVID-19 加强接种量增加了 21%（1.05 个百分点），并溢出使 30 天的流感疫苗接种量增加了 8%在我们的大型研究中（0.34 个百分点）。 需要对促进疫苗接种的干预措施进行更严格的测试，以确保广泛部署基于证据的解决方案，并停止使用无效但直观上有吸引力的工具。