More than any demographic, attitudinal or behavioral variable analyzed in the survey, Americans’ demonstrated understanding of the coronavirus is predictive of mask use — a key insight for public health officials. Most directly relevant to their likelihood to take precautionary measures is Americans’ awareness that COVID-19 can be spread by people who are infected but show no symptoms. Overall, 69% of Americans say this is “definitely true,” while 25% say it is “probably true,” and 6% say it is probably or definitely false.

Though a relatively small proportion of Americans say it is probably or definitely false that the coronavirus can be spread by infected people without symptoms, this belief is associated with a substantially lower likelihood to wear masks in public. Overall, 10% of Americans say they have not worn a mask when outside their home in the past seven days — but this figure rises to 34% among those who believe asymptomatic transmission is false.