“There weren’t suddenly lines around the block,” said Becca Siegel, senior adviser to the US Department of Health and Human Services’ public education campaign.

The data backs up what a recent poll found: While full approval might matter to some unvaccinated Americans, it’s likely not going to be the sole reason unvaccinated Americans will roll up their sleeves.

“For truly undecided people, this is a complex decision. It’s not one thing,” Siegel said.

According to the poll, another factor is more persuasive than full approval: Fear — fear of dying of Covid-19 or of missing out on activities such as travel, concerts or sporting events that require vaccination.