The COVID-19 pandemic threatens millions of lives, and an effective response will require individuals to take costly and difficult measures to slow the rate of transmission. Yet it is unclear how to best motivate preventative actions, which can be conceptualized as either self-interested or cooperative efforts. Should public health messaging focus on the benefits of prevention to individuals, society, or both? We shed light on this question across two pre-registered studies conducted online via Amazon Mechanical Turk (total n = 2176 Americans) during the early days of the COVID-19 pandemic reaching the United States. We investigated the effects of three treatments, consisting of a written appeal and a flier, on intentions to engage in coronavirus prevention behaviors. We presented identical information across treatments, but varied our framing to emphasize the personal, public, or both personal and public benefits of prevention behaviors. While all three treatments increased prevention intentions relative to a no-information control, we found important differences across treatments. In particular, we found strong evidence for the power of prosocial framing: the Public treatment was more effective than the Personal treatment, and the Personal+Public treatment was no more effective than the pure Public treatment. Our results thus suggest that emphasizing the public benefits of prevention efforts may be an effective pandemic response strategy.