Good news has a way of making people do stupid things – particularly amid the coronavirus pandemic. Infection data looking better? Let’s open bars, restaurants, schools, colleges, even the opera! The result: rising cases wherever people let their guard down and gather in ways that facilitate the spread of the virus.

In other words, the feedback loop of human behavior can turn good news very bad. Which is why I think that Robert Redfield, director of the Centers for Disease Control and Prevention, had a point when he said that face masks might provide more protection against COVID-19 than any future vaccine.

My concerns about vaccines aren’t the usual ones. No doubt, they won’t be 100 percent effective. Getting them to all the people needed to achieve herd immunity will be a huge logistical challenge, one that will require much better planning than governments have so far demonstrated, particularly in the U.S. And then there are the considerable pockets of COVID-19 deniers, who will avoid the vaccine even when it’s available, and anti-vaxxers, with their distorted views of risks and rewards – both topics that I’ll leave for another day.

I’m worried about how people will behave when the good news of a viable vaccine comes. It’s the nature of human impatience and need for connection that, as soon as people can possibly rationalize it, they will normalize socializing and intimacy. When they sense that the worst of the threat has passed, that scientists are superheroes, they will throw away their masks and celebrate in the riskiest ways possible. As a result, infections will return to exponential growth.

As many Asian countries have learned through brutal experience, face masks are a powerful tool of prevention. One study has shown that if everyone wears masks that are only 75 percent effective – which many handmade ones are – then the number of people infected by each coronavirus carrier will shrink fourfold. Even if only 80 percent of people wear masks in public, this reproduction rate should be less than 1, the threshold below which the pandemic can’t grow. We’ve seen this in practice.

So if I were in charge of the CDC (thank God that’s not my job), I’d spend all day, every day, reminding people that even once a vaccine is announced, everyone should keep wearing masks. Stay in the habit for at least another year. Of course, given the anti-science leanings of the Trump administration, my entreaties would probably set in motion another feedback loop that would result in my firing. But that’s a risk I’d be willing to take.