Gender. Men are notably more willing than women to say that they will take the vaccine, according to these surveys. For example, 67 percent of men but just 54 percent of women said they would take the vaccine, per Pew. There is not an obvious explanation for this finding, which showed up not only in all four of these polls but surveys done recently of people in Colorado, North Carolina and even Ireland. In fact, this finding contradicts the general trend in American health — women generally take more preventative measures than men. For example, women tend to be more likely than men to get flu vaccinations and men are more likely than women to go a year or more without seeing a doctor.

One potential explanation: women are viewing not taking a vaccine as a pro-health measure, because they aren’t sure that the vaccines are safe. In the Elon University survey of North Carolina residents, women who said they would not take a COVID-19 vaccine suggested that the vaccine approval process had happened too quickly, leaving them worried that the vaccine process was politicized and that there might be side effects that are not being publicized or aren’t yet known.