Governments are considering financial incentives to increase vaccine uptake to end the COVID-19 pandemic. Incentives being offered include cash-equivalents such as vouchers or being entered into lotteries. Our experiment involved random assignment of 1,628 unvaccinated participants in the United States to one of three 45 second informational videos promoting vaccination with messages about: (a) health benefits of COVID-19 vaccines (control); (b) being entered into lotteries; or (c) receiving cash equivalent vouchers. After seeing the control health information video, 16% of individuals wanted information on where to get vaccinated. This compared with 14% of those assigned to the lottery video (odds ratio of 0.82 relative to control: 95% credible interval 0.57-1.17) and 22% of those assigned to the cash voucher video (odds ratio of 1.53 relative to control: 95% credible interval 1.11-2.11). These results support greater use of cash vouchers to promote COVID-19 vaccine uptake and do not support the use of lottery incentives.