Oral Paxlovid (nirmatrelvir-ritonavir) is highly effective at preventing hospitalization and death from COVID-19, yet it has been remarkably underused, even by patients at highest risk from COVID-19, since its December 2021 introduction in the US. The reasons behind this underuse are still unclear. To examine public awareness and perceptions of Paxlovid that might help explain its underuse, we conducted a nationally representative survey of 1,430 US adults in July 2023. A majority of respondents (85 percent) had no or low awareness of Paxlovid, including 31 percent who had never heard of it. Even among those who were aware of the drug, many held misperceptions about its effectiveness (39 percent), adverse effects (86 percent), and requisite timing (61 percent) that could lead to underuse. Lower awareness and misperceptions were more common among medically vulnerable and disadvantaged populations who might benefit most from Paxlovid access, including adults unvaccinated against COVID-19, those with lower levels of education, and Black and Hispanic or Latino adults. Results suggest that Paxlovid underuse may be partly driven by a lack of effective public communication to generate awareness and knowledge about the drug, leading to low demand. As Paxlovid loses full government subsidies, further public outreach is needed to ensure that the public accesses it when needed.