Joseph G. Allen is an associate professor and director of the Healthy Buildings program at Harvard University’s T.H. Chan School of Public Health. He co-wrote “Healthy Buildings: How Indoor Spaces Drive Performance and Productivity.”

It’s time to acknowledge what few in the public health field are willing to say: The campaign to persuade all Americans to voluntarily accept coronavirus vaccinations has hit its limit.

The Biden administration’s vaccine rollout has been remarkable in distributing 400 million doses in the United States. But we have hit a wall with this voluntary approach. The only way out of our covid-19 morass is to mandate vaccines.

There are a number of lessons to glean from the failures of the vaccination strategy. Here are a few:

  • Public health experts have failed to reach half the country. The group with the biggest vaccine “hesitancy” is Republicans. I’ve been in public health for a long time, and I can say with confidence that there are very few openly Republican public health scientists. Maybe we are drawn to this field because our principles align more closely with Democrats’. No matter. Our field is “public” health, not “Democratic” health. Our gross failing to connect with half the country has been on full display. Appearing on left-leaning outlets is not working. Time to get out on Fox News, the Wall Street Journal, Facebook and, yes, even Newsmax.
  • The Food and Drug Administration is going too slow on full approval. These are the most studied and scrutinized vaccines in the history of the world. And what we know with certainty is that these vaccines have an impeccable safety record on par with every other fully authorized vaccine. Yet the FDA has still granted it only authorization for an emergency use. There is no reason for this. Full approval would go a long way to removing a key barrier to vaccination and persuading companies to implement mandates for employees. The FDA must move faster and approve this in August, not as late as the fall, as President Biden recently predicted.
  • Bringing back mask mandates won’t solve the problem. It’s true that vaccinated people “can” transmit the virus, but it’s still unlikely, despite what the Centers for Disease Control and Prevention reported last week. The problem is unvaccinated people. Yes, unvaccinated adults should mask because masks work, but universal masking is not a realistic policy lever right now. Highly vaccinated states will mask; poorly vaccinated states won’t. Does anyone really believe that Missourians were abiding by strict mask mandates and patiently waited for the CDC to lift its mask guidance for vaccinated people in May? To think that the CDC’s guidance caused this wave is so simplistic as to be naive. The cause is the delta variant and people refusing to get vaccinated, not lifting mask mandates.
  • Professional athletes and other “influencers” have been weak advocates. It’s time to call them out. So far they’ve offered a lot of statements to the effect of “that’s a private decision” when asked whether they’ve been vaccinated. LeBron James could probably single-handedly account for tens of thousands of people getting vaccinated — and thousands of lives saved — with a simple pro-vaccine message. Despite being outspoken on many issues of social importance, on whether he was vaccinated, he declined to answer and said, “It’s not a big deal.” And it’s not just athletes. We need a lot more Olivia Rodrigos.

The only way forward is to start embracing mandates. This will inevitably face opposition, and, yes, that includes from unions. It is absolutely appalling to see vaccination rates around the 40 to 50 percent range for unionized workers such as New York City’s police, firefighters and corrections officers, as well as 60 percent for the city’s Education Department workers. Are these the city’s Finest? Bravest? Boldest? Smartest? It’s not looking like it for many of them. Why aren’t union heads out there every single day promoting vaccinations for their members? Unions need to get their house in order.

Just as important are health-care settings. The CDC reported this week that only 45 percent of aides in long-term care health-care facilities are vaccinated. For doctors, its only 75 percent. Some hospital systems are showing similar levels. That’s shocking — and dangerous. Health-care workers are in contact with the most high-risk patients every day. Hospitals and health-care clinics must mandate vaccinations, as nearly 60 top health-care organizations called for in July.

Businesses see this is the only way. Many companies and universities understand that the passive approach has failed and have mandated vaccines for all employees. And it’s legal; the federal Equal Employment Opportunity Commission said so in May, and a federal judge dismissed a lawsuit against Houston Methodist Hospital for requiring vaccines.

Don’t want to call them “mandates”? That’s fine. Then do what MGM Resorts and the National Football League did and, instead of mandating, make the burden of being unvaccinated so high that people comply.

Why are so many people acting like this is some kind of affront to our liberties? It’s routine to get vaccines for all sorts of things. Immunization records are required to go to school, to summer camps and for international travel. We have a silver bullet that can end this crisis. Why are we afraid to pull the trigger?

Last, we’d be foolish to think that’s our only job. We must simultaneously, quickly and decisively lead the effort to vaccinate the world. If we fail to do this, another variant might emerge that escapes our vaccines. And we’ll have to do it all over again.