As more Americans get vaccinated against Covid-19, both President Biden and Gov. Scott are predicting that life will return to normal by this summer. But now a new public health threat is emerging: people who refuse to get vaccinated. Vaccine hesitancy may become a risk factor for getting infected by Covid-19.

There is a striking partisan dimension to vaccine hesitancy: in a recent CBS News poll, a third of Republicans said that they would not be vaccinated — versus 10 percent of Democrats — and another 20 percent of Republicans said they were unsure.

Why are some people reluctant to get vaccinated against a deadly disease? What works to change people's minds?

For answers, we turned to Dan Ariely,  professor of psychology and behavioral economics at Duke University and a founding member of the Center for Advanced Hindsight. He is also a columnist for the Wall Street Journal writing on behavior change. Ariely studies the irrational ways people behave and designs ways to make human behavior more rational.