On Monday, the US Food and Drug Administration gave formal, full approval to the Covid-19 vaccine made by the drug companies Pfizer and BioNTech. You might’ve already gotten a dose of it, of course; millions of Americans have, thanks to an “emergency use authorization” awarded in December 2020. But the new designation was more than just a formality. “If you’re one of the millions of Americans who said they will not get the shot until it has full and final approval from the FDA, it has now happened,” President Joe Biden said when he announced the approval. And, in the same speech: “If you’re a business leader, a non-profit leader, a state or local leader who has been waiting for full FDA approval to require vaccinations, I call on you now to do that—require it.”

Pretty much right away, a lot of places did. Vaccines are safe, effective, and free, but somewhere around 30 percent of Americans haven’t got their shots. Carrots didn’t work; here come the sticks. And they might be able to crush the fourth wave of the Covid pandemic in the US—if they’re done right.

Like the other vaccines still available under EUA, the Pfizer drug is extraordinarily good at keeping people from getting really sick or dying from Covid. But with more than 100,000 people in the hospital with Covid in the US—the most since January—and with the vast majority of them unvaccinated, it’s clear that alone isn’t enough. States, localities, and businesses have tried inducements like prizes, cash, or lotteries, little tricks designed to corral people into doing what’s good for them. In the language of behavioral economics, that’s called a nudge. But in states with low vaccine uptake, those nudges didn’t change the momentum. So now, it’s time for mandates. If you’re one of the 30 percent or so of Americans who haven’t gotten vaccinated yet, get ready for a good hard shove.

And nobody shoves harder than the Pentagon. The Department of Defense immediately announced it’d add Covid-19 vaccines to the more-than-a-dozen already required of servicemembers. Big universities like California’s UC system already had mandates in place, but now more schools have joined: Ohio State, University of Michigan, University of Minnesota. City workforces in Los Angeles and Chicago came under mandate. The new governor of New York announced at her inauguration that she’d institute them, too, and New York City put them in place for public school teachers and the NYPD. In late July, pretty much every major medical and health care professional association signed onto an open letter calling for vaccine mandates across health care; the influential American Medical Association has now reiterated that position. Even the hardcore capitalists at Goldman Sachs won’t let anyone in their offices without proof-of-shot. In journalism, all it takes to make a trend is three examples. I think we’re there.

If that all sounds like jackbootery to you, the history of American public health law and policy says otherwise. Vaccine mandates and other rules that limit personal behavior in the service of societal well-being are super-legal. Just ask Supreme Court Justice Amy Coney Barrett, who reaffirmed that notion two weeks ago with a terse not-gonna-happen in response to a lawsuit brought by students at Indiana University against their school’s vaccine mandate. Barrett’s hard nope upheld an appeals court decision that was in turn based on Jacobson v. Massachusetts, the 1905 Supreme Court decision that gave the OK to requirements for smallpox vaccinations, among other public health regulations. (Most Americans support vaccine mandates, by the way. They are, of course, split along lines of political affiliation. One study this summer suggested that if elite Republicans came out forcefully in favor of vaccines—not just a “personal choice, ask your doctor” move, but full-bore encouragement, it’d increase the number who planned to get vaccinated by as much as 7 percent.) “Nobody has the freedom to go unmasked and unvaccinated in a crowded workspace or classroom. We don’t have the freedom in America to expose other people to an infectious disease,” says Lawrence Gostin, a public health policy expert at Georgetown University.

The point is, formal FDA approval wasn’t necessary for a mandate, but it’s turning out to be sufficient. Businesses, schools, and local governments that wanted to avoid a backlash over requiring “experimental” vaccines now feel like they have an even greener light. (This might’ve been a feint anyway; Texas governor Greg Abbott’s anti-mandate policy used to cite the EUA, and after approval it changed to specify any Covid-19 vaccine.) “They were worried about litigation, they were worried about employee perception, they were worried about public perception,” says Gostin. “We’re going to see, I think, an avalanche of companies and universities following suit in the coming weeks.”

The most important thing about vaccine mandates, though? “They work,” says Saad Omer, director of the Yale Institute for Global Health and an expert in vaccine acceptance. “A lot of the evidence comes from childhood vaccinations. For adults, it comes from influenza vaccinations for health care workers. It shows that having mandates is effective. It gets you from 70 or 80 percent to 90 or 95 percent.”

Public schools across the US require kids to show proof of vaccinations against various illnesses; different states have different levels of permitted opt-outs. One analysis of those requirements showed they increased overall vaccination rates by 18 percent. Flip side: back in 2006, Omer and his colleagues showed that states where it was easier to get exemptions for kids also had higher rates of pertussis, one of the childhood diseases with a widely available vaccine. (It could be worse; Australia fines parents for skipping kids’ vaccinations, and Uganda puts parents in jail.)

There’s a catch: you have to do mandates right. For one thing, mandate policies seen as extraordinarily harsh can spark an anti-vaccine backlash. But the real problem is one size can’t fit all. People are unvaccinated for lots of different reasons. Sure, some of them have political or philosophical disagreements. Some people don’t believe the (very good, very robust) science behind vaccines, or they subscribe to conspiracy theories about their creation. According to a Civiqs poll, 91 percent of people who identify as Democrats have been vaccinated, as have 64 percent of Independents; only 53 percent of Republicans have. And according to a different poll from the Kaiser Foundation, 5 percent of those Republicans say the only way they’d ever get vaccinated is if it was required. So … hi! It is now. Welcome!

But some people aren’t vaccinated because of forces outside their control. Covid-19 has hit certain groups particularly hard—people at lower socioeconomic levels and people of color, especially. They’re at the center of a lot of Venn overlaps: more likely to have the health issues that can make Covid infection deadly, less likely to have ready access to health care, more likely to be in high-risk jobs with lots of exposure, less likely to have good Internet access, more likely to have jobs that pay by the hour and don’t allow sick leave. If you have all that going on, it can be hard to imagine getting a vaccination appointment, much less taking time off if you have side effects that send you to bed. If vaccine mandates deny access to certain spaces, and the unvaccinated are, say, Black people, that’d make the effect of the mandates racist.

The answer? Don’t do that. “You shouldn’t require a vaccination of someone who can’t get access to it,” Gostin says. “Bringing vaccination to the workplace or the campus, or giving paid time off to get the vaccine—including paying for rideshares to get there. You have to focus on access and equity.”

These are fixable policy issues. Goldman Sachs is rich enough to stand up an in-house vaccination clinic. The federal government could make it illegal to fire someone for taking vaccine-related time off, or figure out compensation for lost wages as with jury duty—as President Biden himself has suggested. “To me, equity is the only valid objection against mandates,” Gostin says. “It’s just being attentive to fairness and equity and compassion, and also not to vilify people who are not vaccinated. We don’t want to make this part of a social division in America. Vaccination and mandates are a neutral public health tool, not intended to punish being unvaccinated.”

To do what they’re meant to, mandates need extra policies to support them—and they only work at specific moments in the spread of an outbreak. That’s what Omer, Michelle Mello of Stanford, and Ross Silverman of Indiana University wrote in an article in the New England Journal of Medicine last October, when vaccines against Covid were just a twinkle in the eye of a hypodermic needle and more than half of all Americans said they’d avoid getting a vaccine should one become available. The gist was: a mandate won’t work until there’s enough vaccine to go around (check), evidence for safety has been well-communicated (kind-of check?), voluntary uptake isn’t preventing spread (super-check) and, critically, the government has removed financial or logistical barriers. That varies from state to state, even from business to business. “Right now, those criteria have not been met for the general population,” Omer says. “But they have been met for health care workers, for universities, and for a large group of employers.”

Fortunately, equity might not be as big a problem as some have worried. After early signs of resistance, uptake of Covid vaccines among minorities is actually pretty strong—around the 60 percent level, though it varies regionally. Black people and white people have pretty much the same numbers who say they’d never take the vaccine, around 15 percent. (It’s more like 11 percent among Hispanic people.) For all the fluttering concern about people quitting their jobs if they’re required to get vaccinated, the exact opposite might also be true. “My group has done surveys of employees, and it turns out there are far more people who say they’re likely to quit if there wasn’t a vaccine mandate than if there was. People forget that other side of the coin, they forget that people who want to be safe at work and school far outnumber the opposition,” Gostin says. “In that study, the young people who said they would quit if there was not a mandate was highest among African Americans.”

Opposition to mandates will initially look strong, but it’s important not to overestimate it. Sure, the head of a Chicago police officers’ union issued a statement saying that the city’s mandate had “literally lit a bomb under the membership” because “we don’t want to be forced to do anything.” But loud doesn’t equal widespread. In France, the imposition of a broad vaccine mandate was met with massive protests … and 1.3 million people signing up to get their shots on the first day.

That’s what seems to be happening at United Airlines. The CEO said in January that he planned to mandate vaccinations among all 67,000 of the airline’s US employees, expecting resistance. (None of the other big US carriers have instituted vaccine mandates; Delta is requiring vaccinations, but employees can pay a nominal fine to opt out—basically paying for the added insurance.) “Typically, when you confront situations like this you have a majority of people who agree with you, and then a minority of people who intensely and enthusiastically disagree with you,” says Josh Earnest, chief communications officer at United. “But here’s the punchline, and this became clear after we made the announcement: While there is a vocal and intense minority that opposed the requirement, there’s a much larger constituency of employees who don’t just support the policy, but support it enthusiastically.”

The company had laid the groundwork for that outcome. United set up vaccination clinics at airports where it had large numbers of workers. The company put out educational materials on vaccines. It held talks with the unions that represent pilots and flight attendants. But that doesn’t mean United won’t eventually suffer; airlines are already dealing with staffing issues significant enough to mess up flight schedules. Losing pilots over vaccines would hurt. “The truth of the matter is, it’s too early to say yet how vaccine hesitancy or objection, how large of a group that is, even at United,” Earnest says. “We probably won’t find out until the deadline hits, which will be the end of September.”

In a way, that internal tension between a vocal opposition and a less vocal but larger group that supports mandates is a whole other kind of equity issue. “People who are poorer, or members of minority groups that suffer discrimination, those are also the groups that suffer the most Covid risk from the lack of mandates,” says Govind Persad, a health law and policy professor at the Unversity of Denver. “People often have this initial reaction that mandates are inequitable because they treat people differently. But the challenge for that is: Covid is also inequitable.” Looked at that way, and given the way Covid’s fourth wave is moving through specific regions in the US, the argument for mandates may be stronger than ever.

This story originally appeared on wired.com.

https://arstechnica.com/?p=1790329