Financial incentives for vaccination do not have negative unintended consequences.

Financial incentives to encourage healthy and prosocial behaviours often trigger initial behavioural change1-11, but a large academic literature warns against using them12-16. Critics warn that financial incentives can crowd out prosocial motivations and reduce perceived safety and trust, thereby reducing healthy behaviours when no payments are offered and eroding morals more generally17-24. Here we report findings from a large-scale, pre-registered study in Sweden that causally measures the unintended consequences of offering financial incentives for taking the first dose of a COVID-19 vaccine. We use a unique combination of random exposure to financial incentives, population-wide administrative vaccination records and rich survey data. We find no negative consequences of financial incentives; we can reject even small negative impacts of offering financial incentives on future vaccination uptake, morals, trust and perceived safety. In a complementary study, we find that informing US residents about the existence of state incentive programmes also has no negative consequences. Our findings inform not only the academic debate on financial incentives for behaviour change but also policy-makers who consider using financial incentives to change behaviour.

Monetary incentives increase COVID-19 vaccinations.

The stalling of COVID-19 vaccination rates threatens public health. To increase vaccination rates, governments across the world are considering the use of monetary incentives. Here we present evidence about the effect of guaranteed payments on COVID-19 vaccination uptake. We ran a large preregistered randomized controlled trial (with 8286 participants) in Sweden and linked the data to population-wide administrative vaccination records. We found that modest monetary payments of 24 US dollars (200 Swedish kronor) increased vaccination rates by 4.2 percentage points (P = 0.005), from a baseline rate of 71.6%. By contrast, behavioral nudges increased stated intentions to become vaccinated but had only small and not statistically significant impacts on vaccination rates. The results highlight the potential of modest monetary incentives to raise vaccination rates.

Anticipation of COVID-19 vaccines reduces willingness to socially distance.

We investigate how the anticipation of COVID-19 vaccines affects voluntary social distancing. In a large-scale preregistered survey experiment with a representative sample, we study whether providing information about the safety, effectiveness, and availability of COVID-19 vaccines affects the willingness to comply with public health guidelines. We find that vaccine information reduces peoples' voluntary social distancing, adherence to hygiene guidelines, and their willingness to stay at home. Getting positive information on COVID-19 vaccines induces people to believe in a swifter return to normal life. The results indicate an important behavioral drawback of successful vaccine development: An increased focus on vaccines can lower compliance with public health guidelines and accelerate the spread of infectious disease. The results imply that, as vaccinations roll out and the end of a pandemic feels closer, policies aimed at increasing social distancing will be less effective, and stricter policies might be required.

Parameterizing standard measures of income and health inequality using choice experiments.

When measuring inequality using conventional inequality measures, ethical assumptions about distributional preferences are often implicitly made. In this paper, we ask whether the ethical assumptions underlying the concentration index for income-related health inequality and the Gini index for income inequality are supported in a representative sample of the Swedish population using an internet-based survey. We find that the median subject has preferences regarding income-related health inequality that are in line with the ethical assumptions implied by the concentration index, but put higher weight on the poor than what is implied by the Gini index of income inequality. We find that women and individuals with a poorer health status put higher weight on the poor than men and healthier individuals. Ethically flexible inequality measures, such as the s-Gini index and the extended concentration index, imply that researchers have to choose from a toolbox of infinitely many inequality indices. The results of this paper are indicative of which indices (i.e. which parameter values) reflect the views of the population regarding how inequality should be defined.

Prosociality predicts health behaviors during the COVID-19 pandemic.

Socially responsible behavior is crucial for slowing the spread of infectious diseases. However, economic and epidemiological models of disease transmission abstract from prosocial motivations as a driver of behaviors that impact the health of others. In an incentivized study, we show that a large majority of people are very reluctant to put others at risk for their personal benefit. Moreover, this experimental measure of prosociality predicts health behaviors during the COVID-19 pandemic, measured in a separate and ostensibly unrelated study with the same people. Prosocial individuals are more likely to follow physical distancing guidelines, stay home when sick, and buy face masks. We also find that prosociality measured two years before the pandemic predicts health behaviors during the pandemic. Our findings indicate that prosociality is a stable, long-term predictor of policy-relevant behaviors, suggesting that the impact of policies on a population may depend on the degree of prosociality.

Trait self-control, exercise and exercise ambition: Evidence from a healthy, adult population.

This study explores if self-control predicts exercise ambition and actual exercise, and if exercise ambition predicts actual exercise. Members and guests at a not-for-profit sports club were invited to participate. 264 individuals completed a self-reported (Self-Control Scale) measure of self-control, and responded to questions about actual exercise as well as exercise ambition prior to their workout. Main Outcome Measures are exercise ambition, actual exercise, and the difference between them. We find that trait self-control predicts both actual exercise and exercise ambition. Exercise ambition also predicts actual exercise. The results suggest a path from self-control, via exercise ambition, to actual exercise. Individuals with relatively low self-control might benefit from some aid in setting goals for their workouts and committing to exercise.