International agencies are now poised to counter such profit-motive failures in the vaccines markets, drawing their funding mostly from the Gates Foundation and the foreign aid budgets of a handful of wealthy countries. The Coalition for Epidemic Preparedness Innovations (CEPI), which grew out of the World Economic Forum, offers financial support for vaccine invention. Gavi, the Vaccine Alliance, makes bulk purchases of childhood vaccines and helps ensure their distribution in poor countries. The Global Fund underwrites some health system costs for poor countries, primarily in sub-Saharan Africa. Together, they represent a fledgling international infrastructure for global immunization.

But Covid-19 won’t simply disappear if the wealthy world is left to its own devices, manufacturing costly vaccines that are only affordable to fully insured residents of the 30 richest nations on Earth. What we collectively face is the need to execute the largest mass immunization program in world history, deploying teams of vaccinators to every nook and cranny of the planet, rich or poor.

The last time any such gargantuan feat was attempted was following a Soviet and American 1966 call for smallpox eradication, led by WHO. Thousands of vaccinating teams deployed all over the world, eventually in 1977 vanquishing the virus that killed more human beings in the twentieth century than all wars combined. As totemic as smallpox eradication is in the annals of global public health, it was accomplished at a time when three billion fewer people lived on the planet, and many of them lived in countries that conducted routine childhood immunization. This meant that the immunization initiative undertaken from 1966 to 1977 targeted about one billion people.

If an effective Covid-19 vaccine is developed, its targets will include almost eight billion human beings, with nearly three-quarters of a billion living in conditions of extreme poverty, according to World Bank figures. Eliminating the coronavirus scourge will require mobilization of tens of thousands of immunization teams, armed with affordably priced vaccines. It is likely that both China and the United States, based on their initial human tests of candidate vaccines, will lead global manufacturing—and that both countries will face the moral and economic pressures of balancing global needs against company profits.

In the best of all possible worlds, Presidents Xi and Trump can rise to this epochal challenge, and see their way clear to formalize an agreement to execute the largest humanitarian effort in world history to arrest the spread of the SARS-CoV-2 virus. And in that long-shot scenario, we might even see these two power-mad egomaniacs share a Nobel Peace Prize.