This 2023 survey captures the broad reach of health misinformation, with at least four in 10 people saying that they’ve heard each of 10 specific false claims about COVID-19, reproductive health, and gun violence. At the same time, roughly half to three-quarters of the public are uncertain whether each of the 10 false claims are true or not, describing them as either “probably true” or “probably false.” This suggests that even when people don’t believe false claims they hear, it can create uncertainty about complicated public health topics.