That risks increasing public distrust, she said, at a time when governments need perhaps three-quarters of their populations to voluntarily vaccinate.
Still, passport-style policies would, in theory, help control the pandemic as a whole, reducing overall infections and economic disruptions that fall inordinately on underprivileged groups.
The only way to untangle that dilemma, Dr. Errett said, is “addressing the inequality itself,” closing the racial and class disparities that have widened throughout the pandemic.
Then there is inequality among nations, mostly relevant for international travel.
The approved coronavirus vaccines have been, with some exceptions, generally distributed among nations rich enough to buy or produce them. The world’s poorest may be two or three years out, though their residents are also less likely to travel across borders.
Yet there are billions in the middle: with the means to travel, and sometimes the need, but not access to shots.
“If we are opening up the world only to people from high-income countries, we are creating a lot of inequity,” Dr. Errett said. “We’re cutting people off from resources and from connections that keep economies and communities thriving.”