A 680,000-person megastudy of nudges to encourage vaccination in pharmacies.
Katherine L MilkmanLinnea GandhiMitesh S PatelHeather N GraciDena M GrometHung HoJoseph S KayTimothy W LeeJake RothschildJonathan E BogardIlana BrodyChristopher F ChabrisEdward H ChangGretchen B ChapmanJennifer E DannalsNoah J GoldsteinAmir GorenHal HershfieldAlex HirschJillian HmurovicSamantha HornDean S KarlanAriella S KristalCait LambertonMichelle N MeyerAllison H OakesMaurice E SchweitzerMaheen ShermohammedJoachim TalloenCaleb WarrenAshley V WhillansKuldeep N YadavJulian J ZlatevRon BermanChalanda N EvansRahul LadhaniaJens LudwigNina MazarSendhil MullainathanChristopher K SniderJann SpiessEli TsukayamaLyle H UngarChristophe Van den BulteKevin G M VolppAngela L DuckworthPublished in: Proceedings of the National Academy of Sciences of the United States of America (2022)
Encouraging vaccination is a pressing policy problem. To assess whether text-based reminders can encourage pharmacy vaccination and what kinds of messages work best, we conducted a megastudy. We randomly assigned 689,693 Walmart pharmacy patients to receive one of 22 different text reminders using a variety of different behavioral science principles to nudge flu vaccination or to a business-as-usual control condition that received no messages. We found that the reminder texts that we tested increased pharmacy vaccination rates by an average of 2.0 percentage points, or 6.8%, over a 3-mo follow-up period. The most-effective messages reminded patients that a flu shot was waiting for them and delivered reminders on multiple days. The top-performing intervention included two texts delivered 3 d apart and communicated to patients that a vaccine was "waiting for you." Neither experts nor lay people anticipated that this would be the best-performing treatment, underscoring the value of simultaneously testing many different nudges in a highly powered megastudy.