Ezekiel J. Emanuel is vice provost at the University of Pennsylvania and a former member of Joe Biden’s public health advisory committee. John P. Moore is a professor of microbiology and immunology at Weill Cornell Medicine.

To overcome covid-19, at least 80 percent of Americans need to be vaccinated. We are now at 54 percent. Voluntary efforts have proved to be insufficient. It is inevitable we will need another mandate — this time for domestic travel by planes, trains and buses.

Although vaccine hesitancy is at least partially the product of a unique moment of disinformation and polarized politics, what we are witnessing is not unusual. Appealing to people’s better nature has rarely persuaded 80 percent of Americans to do the right thing, even when the benefits are obvious. While World War II had overwhelming popular support, we needed a military draft because there weren’t enough volunteer soldiers. Similarly, we have requirements and enforcement throughout society — laws against drinking and driving, for wearing a seat belt, for mandatory schooling that includes required childhood immunizations, obtaining consent before sex — because we can’t count on voluntary compliance.

President Biden has mandated coronavirus vaccines for many Americans because persuasion has been insufficient to get vaccine uptake to 80 percent. But as welcome as the president’s measures were, they will not be enough. Mandating vaccinations for flying and other forms of interstate travel is now critical if we are to prevent a predictable surge of infections and deaths during the coming winter holiday periods.

Last year, AAA estimated that 50 million Americans would travel over Thanksgiving, while more than 80 million would do so in the Christmas and New Year period. About 9.5 million people took flights at Thanksgiving, and about 10.2 million flew in the days around Christmas. The outcome was huge surges in infections, reaching 3,500 deaths per day by January — more than the number of Americans killed on 9/11.

Last year’s winter holiday travel occurred largely before vaccines were available to the public. This year, many more people are expected to travel, especially by flying. A large proportion of these travelers will be highly vulnerable to infection and disease, because nearly 80 million American adults remain unvaccinated, and 48 million children younger than 12 are not yet eligible for vaccines. The only way to avert a repeat of last winter’s carnage is a substantial increase in vaccinations and rigorous enforcement of mask mandates both for adults and children.

It takes roughly six weeks from the first shot for maximal protection to kick in. That is why the Biden administration must announce a travel mandate now so that more Americans are protected by Thanksgiving. If proving one’s vaccination status were required to board a plane or take an interstate train or bus, many vaccine-refusing Americans would face a choice between remaining unvaccinated and being able to travel conveniently. Unvaccinated members of Congress may elect to thumb a ride home to Florida for the holidays, or arrange for a chauffeur to drive them from the Capitol to Georgia. But others may decide it’s finally time to do the right thing and take advantage of these safe, free and effective vaccines, and encourage their constituents to do the same.

Requiring vaccination for travel is hardly radical. The U.S. government has been considering a mandate for people flying into the United States from foreign countries. It’s already required for Americans to fly internationally if they don’t want to quarantine for 10 or more days in Germany, Britain and other destinations. These policies have allowed international travel to resume. More than a month ago, Canada announced a vaccine mandate for interprovincial travel on all forms of public transport. We should follow our neighbor’s lead.

Such a mandate would be straightforward to create, based on protecting federal employees from the infection risks created by unvaccinated travelers. Transportation Security Administration staff are exposed daily to thousands of unvaccinated people who pass through security checkpoints.

Of course, there will be pushback. But cries of “freedom” and “personal choice” are hollow and politically motivated. Our freedom is not unlimited. We live in a society of “ordered liberty” with reasonable restrictions on our conduct. We all have responsibilities to the well-being of others; never is this moral imperative more important than during a pandemic. Vaccination protects not just ourselves but others we come into contact with, including young children, cancer patients and other immunocompromised Americans who cannot be vaccinated themselves. Should we just ignore their rights to live safely?

There is a short window to boost coronavirus vaccination rates to make interstate travel safer. Introducing mandates today will reduce infections and, most importantly, hospitalizations and deaths in November and beyond. The Biden administration must act now to avert the mass death we saw last winter, especially as we battle the more transmissible delta variant. By giving unvaccinated Americans tougher choices about their movement and daily lives, we may finally have the lever we need to increase vaccination rates and turn the corner in this pandemic.