Although the lotteries and cash giveaways generated much fanfare, and governors boasted of their effectiveness, a flurry of academic studies now suggests that most large-scale financial-incentive programs had minimal impact, or were total duds. It’s not clear why the incentive programs seemed to fail, but Mireille Jacobson and Tom Chang, two economists at the University of Southern California, have some suspicions.

Over the summer, they recruited 2,700 participants and randomly divided them into several groups—some were offered up to $50 in cash to get vaccinated, while others viewed public-health messages or received scheduling links that would make finding an appointment easier. The study itself took two months, but the analysis was basically ready in hours. “We could tell pretty quickly that there was no there there,” Chang told me. They found that for Donald Trump voters, the guaranteed $50 financial incentive actually decreased vaccination rates. “It’s not normal to pay someone to do something that’s good for them,” Chang said. If a vaccine is so good, the thinking goes, “then why do you have to pay people to take it?”

But that’s not to say we should give up on incentives altogether—especially now that the future of mandates seems shakier than ever. Even though statewide lotteries and beer giveaways proved to be gimmicky busts, there could still be a role for better-designed incentive programs, especially those that target specific populations.