Monetary incentives increase COVID-19 vaccinations

Abstract

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.

Fig. 1.. Vaccination uptake and intentions to get vaccinated, among those in the incentives condition and the control condition.

The graphs show the proportion of participants in the incentives and control conditions who got vaccinated or intended to get vaccinated, on the basis of survey data from the trial linked to Swedish administrative records on vaccination. “Vaccination Uptake” indicates the proportion of participants who got vaccinated within 30 days of the trial, according to vaccination records. “Intentions to Vaccinate” indicates the proportion of participants who intended to get vaccinated within 30 days of the trial, according to experimental data. Error bars represent normal-based 90% confidence intervals (CIs; mean ± 1.64 SE) from OLS regressions with heteroscedasticity-robust standard errors. N = 1131 participants in the incentives condition; N = 2778 participants in the control condition.

Fig. 2.. Regression-estimated effects of experimental conditions on vaccination uptake and vaccination intentions versus the control condition.

The graph shows regression-estimated effects (OLS regression) of the experimental conditions relative to the control condition, as preregistered. In addition, “All Nudges” denotes the estimate when the social impact, argument, and information conditions are pooled. Filled circles indicate the estimated impact on vaccination uptake within 30 days after participation in the survey (100 if the participant got vaccinated, 0 otherwise). Open circles indicate the estimated impact on intended vaccination uptake (100 if the participant intended to get vaccinated, 0 otherwise) within 30 days. Error bars represent 90% normal-based CIs (coefficient ± 1.64 SE) from OLS regressions with heteroscedasticity-robust standard errors. N = 8286 participants.

Fig. 3.. Regression-estimated effects of experimental conditions on whether participants clicked a link to a website with information for scheduling a vaccine appointment.

The graph shows regression-estimated effects (OLS regression) of the experimental conditions relative to the control condition, as preregistered. In addition, “All Nudges” denotes the estimate when the social impact, argument, and information conditions are pooled. Circles indicate the estimated impact of each experimental condition on the probability of clicking the appointment link (100 if the participant clicked the link, 0 otherwise). The no-reminders condition is not included because this condition did not include the link. Error bars represent 90% normal-based CIs (coefficient ± 1.64 SE) from OLS regressions with heteroscedasticity-robust standard errors. N = 7288 participants.