Six months into America's COVID-19 pandemic, cases are surging, small businesses are faltering, playgrounds are empty, and unemployment is at 11 percent. Our best hope for ending this nightmare is a vaccine, and there are more than 165 in development.

But when a vaccine becomes available, how many Americans will refuse it?

Vaccines are the greatest health care advance of our time, preventing an estimated 4.5 billion infections since their advent. So what explains the reluctance of so many Americans to vaccinate? 

It's a combination of bad science, the government's long history of misleading the public, and the collapse of confidence in public health authorities because of their catastrophic failures in response to the COVID-19 pandemic. 

But if the government responds by attempting to force Americans to take a COVID-19 vaccine, it will only help the conspiracy theorists. Public health officials can begin to undo the damage of the past six months by rejecting authoritarian and paternalistic approaches in favor of careful persuasion and brutal honesty about the limits of their own knowledge.

Though most Americans surveyed say they'll probably take the vaccine, there's a real possibility that a sizable bloc of refusers could allow this novel coronavirus to continue spreading, based on what's happened with measles, cases of which surged to record levels in America in 2019 largely due to pockets of vaccine refusal, which tends to happen in clusters, according to researcher Tara C. Smith.