Now that the Food and Drug Administration has approved the Pfizer-BioNTech coronavirus vaccine, the U.S. military, some schools and various employers are beginning to mandate vaccination. Meanwhile, with the highly contagious delta variant spreading rapidly, in July, President Biden called on state and local governments to offer $100 cash payments to those who get vaccinated. Do either of these approaches actually help persuade vaccine skeptics to get the shot?

The president’s suggestion builds on what various states and localities have been doing. A number of governors have offered savings bonds or cash to young adults and state workers, respectively, in exchange for getting vaccinated. D.C. offered $51 gift cards to anyone getting their first shot. Many states have held lotteries with prizes of $1 million or more to encourage vaccination.

This past spring, a team of UCLA researchers released survey data showing a cash payment of $25 to $100 could encourage roughly a third of unvaccinated respondents to get vaccinated.

Can more such payments increase vaccination rates, or would other ways be more successful? Our research suggests that cash is king — especially among groups currently unlikely to get the shot, including Republicans and independents.

How we did our research

In January, we fielded a survey to a nationally representative sample of 1,000 Americans, using Lucid Marketplace. Respondents participated in the survey online. Because the survey was administered in January, vaccine eligibility was still mostly restricted to health-care workers and nursing home residents. We assume most if not all of our respondents were unvaccinated, giving us the opportunity to measure what could make them more or less likely to get vaccinated once they were eligible.

We had each respondent choose between two vaccination scenarios, asking which one would make them more likely to get the shot. We randomly varied six aspects of those scenarios in something that social scientists call a “conjoint experiment,” which allows researchers to compare many possibilities in a statistically valid way.

In each vaccine scenario, respondents read a different version of these factors:

  • Number of shots required: one or two
  • Vaccine brand: Pfizer, Moderna or AstraZeneca
  • Hypothetical proportion of the U.S. already vaccinated: 0 percent, 25 percent, 50 percent or 80 percent
  • Whether employers were generally mandating vaccination
  • Where and when they’d get the vaccine: either a state-organized clinic or a physician’s office, either drop-in or with appointments required
  • A financial incentive: nothing, $20 cash or a $20 gift card for local businesses

Before the respondents read any scenarios, we asked how likely they were, on a seven-point scale, to get vaccinated. We used those responses to categorize our sample into likely, unlikely, and neutral groups. We also asked a number of demographic questions, including whether they identified with or leaned toward the Republican or Democratic party.

In the full sample, about 26 percent of respondents stated they were “unlikely” to get vaccinated; 66 percent were “likely” to be vaccinated; and the remaining 8 percent suggested ambivalence by saying in that they were “neither unlikely nor likely” to get vaccinated.

As other research has found, those vaccination intentions broke down differently by party affiliation. Among our respondents, 77 percent of Democrats said they were “likely” to be vaccinated, compared with only 61 percent of Republicans and 59 percent of independents. Moreover, while 57 percent of Democrats said they were “extremely likely” to be vaccinated when eligible, only 39 percent of Republicans and 38 percent of independents said the same. Lastly, Republicans and independents were more likely to express ambivalence about the shots than Democrats, with 12 and 9 percent of Republicans and independents choosing “neither unlikely nor likely” compared with just 5 percent of Democrats.

Small cash payments made a difference

We focused on the responses from those who said they were unlikely to get vaccinated, as we wanted to see which incentives, if any, might persuade them to change their minds.

First, employer mandates did not make our respondents more likely to say they’d get vaccinated. In fact, for Republicans and independents, employer mandates seemed to harden attitudes against vaccination by 5 to 10 percent.

Second, respondents were about 10 percent less likely to say they would get vaccinated if it required two doses than if it took just one shot. That may be useful information for public health officials considering authorizing booster shots. Every additional shot decreased the likelihood of a person getting vaccinated, even for Democrats or anyone who said they were likely to get vaccinated.

Third, to our surprise, making it easier to get the shot did not affect whether they said they were likely to get vaccinated. We had assumed that convenience would make a difference, as do Biden and public health officials who have been advocating a door-to-door vaccination campaign.

But even among those who initially said they were unlikely to get vaccinated, a cash payment of $20 made respondents more likely to get the shot by 10 percent among Republicans, 11 percent among Democrats, and 20 percent among independents. While a previous study found that $100 payments made people 19 percent more likely to say they’d be vaccinated, even $20 can make a difference.

Carlos Algara (@algaraca) is an assistant professor of politics and government at Claremont Graduate University.

Daniel J. Simmons (@djsimmons00) is an assistant professor of political science at Saint Michael’s College.