And then there’s another challenge: convincing Americans to actually get a vaccine once one receives emergency authorization. According to a new CNN poll released Monday, only 51% of those surveyed said they would try to get vaccinated if a low-cost therapy is widely available while 45% said they wouldn’t.

That’s a drop from August, when 56% said they would try to get a vaccine, and a significant falloff from May, when 66% said the same.

It’s unclear what’s driving that trend, though racial, age-related, and political demographics all seem to play a part. A far higher number of older Americans would try to get vaccinated compared to younger respondents.

The trouble with just a 51% participation rate is that it’s not high enough of a number to achieve herd immunity, wherein vaccinated people offer protection to the more vulnerable.

One solution may be education and outreach programs touted by executives as Johnson & Johnson CEO Alex Gorsky and Pfizer’s biopharmaceuticals division president Angela Hwang (both companies are working on COVID vaccines) have told recent panels held by Fortune.

Previous polling has also found that 60% of American voters prefer a proven and safe coronavirus vaccine than one that’s been rushed to market.

To that end, Tuesday’s new FDA guidance seems to hit that standard in defiance of Trump’s insistence at a quickly made vaccine.

One of the most significant elements of those guidelines—and one that would almost certainly delay a vaccine till past Election Day—is that follow-up period for trial participants before the FDA even considers an experimental treatment. But, as the previous polls show, that’s a measure most Americans find prudent.