Tamara Keith

Under pressure to share AstraZeneca vaccine doses not yet being used to inoculate Americans, the Biden administration is finalizing plans to loan millions of doses of the COVID-19 vaccine to Mexico and Canada. It's a first foray into vaccine diplomacy for the Biden administration, weeks after global competitors China and Russia began using vaccine doses to exert influence.

Finding the right message — and right messengers — to persuade skeptical conservatives to get the COVID-19 vaccine has become an urgent concern for public health experts pushing to contain the coronavirus.