Megastudy shows that reminders boost vaccination but adding free rides does not.

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 vaccines1,2. 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.

What's in a name? Branding reclaimed water.

Reclaimed water is often presented as a cost-effective, reliable, and safe solution to increasingly common water shortages in the United States and across the globe, but studies have shown that consumers tend to object to the use of this water. Broad adoption of this technology will require consumer acceptance or at least tolerance of it, and studies have suggested that better branding could minimize consumers' concerns. In this study, we first test twenty-one potential branding names for reclaimed water using survey responses to identify the top-six most favored names. We then determine whether an opportunity for consumers to try reclaimed water can change their preferences. The results suggest that the common names for this water, such as Recycled, Reclaimed, Nontraditional, Treated Wastewater, and Reused, are the least appealing, as they all scored at the bottom. In contrast, names that invoke desirable characteristics of the water-Pure, Eco-Friendly, and Advanced Purified, were viewed significantly more favorable than the others. Having an opportunity to taste reclaimed water treated to a potable standard seems to clarify consumers' preferences by increasing the differences in favorability between the names. Based on these results, it appears that while there are a couple of appealing names, the most consistently preferred is Pure Water.

A citywide experiment testing the impact of geographically targeted, high-pay-off vaccine lotteries.

Lotteries have been shown to motivate behaviour change in many settings, but their value as a policy tool is relatively untested. We implemented a pre-registered, citywide experiment to test the effects of three high-pay-off, geographically targeted lotteries designed to motivate adult Philadelphians to get their COVID-19 vaccine. In each drawing, the residents of a randomly selected 'treatment' zip code received half the lottery prizes, boosting their chances of winning to 50×-100× those of other Philadelphians. The first treated zip code, which drew considerable media attention, may have experienced a small bump in vaccinations compared with the control zip codes: average weekly vaccinations rose by an estimated 61 per 100,000 people per week (+11%). After pooling the results from all three zip codes treated during our six-week experiment, however, we do not detect evidence of any overall benefits. Furthermore, our 95% confidence interval provides a 9% upper bound on the net benefits of treatment in our study.