During the COVID-19 pandemic, individuals have depended on risk information to make decisions about everyday behaviors and public policy. In this online informational intervention, we assessed whether an interactive website influenced individuals' risk tolerance to support public health goals. We collected data from 10,891 unique users who interacted with the online COVID-19 Event Risk Tool (https://covid19risk.biosci.gatech.edu/), which featured interactive elements (a dynamic risk map, survey questions, and a risk quiz with accuracy feedback). After learning about the risk of COVID-19 exposure, participants reported being less willing to participate in potentially risky events. This increase in risk aversion was most pronounced for large event sizes and for individuals who had underestimated risk. We also uncovered a bias in risk estimation: Participants tended to overestimate the risk of small events, but underestimate the risk of large events. Our results bear implications for risk communication and insights for broader research on risky decision-making.