What are the biggest threats to the health security of the American people? There are some strong candidates. Avian influenza is spreading in birds, cattle, and 50 mammalian species. Measles cases are surging at home and abroad. COVID-19 is still spreading and could mutate into a more deadly strain. Farther afield, Uganda continues to respond to an Ebola outbreak and Mpox has been seen in 127 countries. But perhaps the biggest threat to America’s health could be self-inflicted. According to a report published yesterday in the New York Times, our leaders intend to end funding for international immunization programs—including the Gavi Alliance I led from 2011 to 2023—that for decades have protected Americans from health threats abroad. These cuts would represent a grave threat to the health, well-being, and livelihoods of every American.

Secretary of State Marco Rubio has made it clear that U.S. national interest would be the guiding mission of American foreign policy. “Every dollar we spend, every program we fund, and every policy we pursue must be justified with the answer to three simple questions,” he said. “Does it make America safer? Does it make America stronger? Does it make America more prosperous?” For decades, U.S. support for immunization abroad has answered every one of these questions with a resounding “yes,” and U.S. philanthropies and the U.S. government have played a key role in funding vaccines for many of the world’s poorest children.

Vaccines are our first line of defense when it comes to prevention of infectious disease, and the last word when the time comes to respond to an escalating outbreak or pandemic. In a world that changes fast, we know the next pandemic is a question of when, not if.

Consider the case of Gavi, an international alliance of public- and private-sector partners that has been at the forefront of this global vaccination effort. Gavi, which received $300 million from the U.S. in 2024, uses an innovative financing model to dramatically reduce the cost of these vaccines and then gradually transfer the costs of immunization programs to their respective national governments as they transition from low-income to middle-income economies. The alliance provides vaccines for half of the world’s children and has immunized more than 1.1 billion additional children and counting in the past 25 years. In the process, it has achieved a return on investment that would be the envy of Wall Street: $54 for every dollar spent.

Of course, as a former CEO of Gavi, I’m biased. But by any objective measure, Gavi’s results have been extraordinary not only in terms of the projection of soft U.S. power, but also in terms of the preservation of the vital security interests of America and our allies.

The front line of the fight against many infectious diseases might be far from U.S. borders, but every case of measles and avian influenza on U.S. soil tells us the same simple story: viruses don’t care about borders. Because we live in a connected world, immunization in poorer countries is a big part of how we stop outbreaks of preventable but devastating diseases abroad, but also on U.S. soil–diseases that can cost lives and could end up costing us billions to contain. In other words, stronger immunization coverage in Khartoum and Kinshasa saves lives there, but also in Kansas City.

Think back to just over 10 years ago. In 2014, three West African countries were devastated by an Ebola outbreak that claimed more than 11,000 lives. We saw cases in the U.S. and six additional countries, and we saw fear and panic amplified by the fact that there was no vaccine to control the disease. Gavi not only helped get an experimental vaccine across the finish line, it established a global vaccine stockpile that has played a key role in the rapid containment of outbreaks since. So far not a single additional case has made its way to the U.S.