Midway into 2026, the most overt attacks on vaccines in the United States have stopped. With the midterm elections looming, the White House reportedly asked Health Secretary Robert F. Kennedy Jr. to quiet his anti-vaccine rhetoric—publicly, at least. But protections against infectious disease are continuing to falter, both domestically and abroad, through sheer neglect. Although the full impact of the U.S.’s disinterest has only started to play out, one effect is already clear: When vaccines’ reach is eroded, the poorest, least well-served people feel the brunt of that loss first.Paring back the CDC’s national childhood immunization schedule, for instance, has limited more Americans’ access to shots; Kennedy’s haphazard reconstitution of the nation’s top vaccine advisory panel led to that expert group being put on hiatus, imperiling immunizations for children from underinsured families. When the White House dismantled the U.S. Agency for International Development, accusing the organization of waste and abuse, it compromised efforts to deliver vaccines around the world; when it stopped funding the World Health Organization, citing the group’s mishandling of the coronavirus pandemic, it put global immunization campaigns at risk. But among the more than half a dozen experts I spoke with for this story, the chief concern was for Gavi, the Vaccine Alliance, the world’s largest initiative supporting immunization access in lower-income countries.Since last year, the U.S. has been withholding hundreds of millions in funds from the organization. The U.S. played a vital role in Gavi’s founding and has historically been one of its heaviest funders: In 2024, under President Biden, the country pledged nearly $1.6 billion to Gavi, to be meted out over five years. That contribution should have covered roughly 13 percent of the organization’s funding through 2030. But the U.S. State Department hasn’t sent the $600 million that Congress budgeted for Gavi in fiscal years 2025 and 2026. (If left unused, the funds will expire on September 30; earlier this month, senators from both parties called on the State Department to relinquish the appropriated money to Gavi.)Kennedy himself is not in charge of the State Department’s funds, but he has repeatedly accused Gavi, without evidence, of having “ignored the science” on immunizing children, of being lax on vaccine safety issues, and for relying on a combination diphtheria-tetanus-pertussis vaccine (known as DTwP) that he has accused of causing brain damage in kids, despite data to the contrary. The Trump administration’s policies toward Gavi have also, at times, mirrored Kennedy’s agenda at the Department of Health and Human Services: Several months ago, officials asked Gavi to halt its use of vaccines that contain the preservative thimerosal, a compound that Kennedy helped push to phase out of U.S. flu shots last year and that he and many of his anti-vaccine allies argue can cause autism, despite a lack of data showing any such connection; at the time, an HHS official told Reuters that future funding for Gavi would be withheld until “a plan for removal of thimerosal-containing vaccines is developed and the plan initiated.”In an email, Andrew Nixon, HHS’s Deputy Assistant Secretary for Media Relations, wrote that HHS and State are still “cautiously optimistic” that ongoing discussions with Gavi could yield “a constructive path forward,” but that “Gavi has not provided the United States with the specific data, studies, or detailed accounting needed to fully evaluate how U.S. taxpayer funds are being used.” The State Department did not respond to a request for comment.The U.S. itself has largely or entirely replaced DTwP and thimerosal with newer, more expensive alternatives that, in some cases, have fewer short-term side effects. But in lower-income, lower-resource places, where medical facilities are short on money, refrigeration, and space, some of these older vaccines are the best options, simply because the alternative is no vaccination at all. So whereas Kennedy’s attacks on these particular tools of vaccination have had a relatively marginal effect on immunization in the U.S., they have the potential to significantly curtail vaccination in other countries, and potentially lead to countless unnecessary deaths.To vaccinate widely in low-resource settings, “you need inexpensive products, and you also need products that don’t require a lot of boosters,” Seth Berkley, an infectious-disease expert who previously led Gavi, told me. Using the cheaper vaccines can have trade-offs; all vaccines do. The DTwP shot, for instance, is more likely to cause short-lived fevers and pain than other formulations of the vaccine. But it protects people for far longer than those other immunizations and requires fewer total shots—which is to say, fewer follow-up visits. The World Health Organization has continued to recommend the vaccine, citing its popularity, price point, and excellent efficacy—and noted that it works well even in situations where vaccination is interrupted or pared back, as it often is in countries with reduced health-care access; in the past 50 years, DTwP is estimated to have saved some 40 million lives. The case for using thimerosal also rests on practicality: It allows clinicians to safely immunize more people without wasting freezer space, because it stamps out contamination in vials that contain multiple doses of the vaccine.The U.S. is now effectively holding funds hostage until Gavi changes up its vaccination strategy—a change that Gavi can’t make overnight. And abruptly halting the distribution of vaccines with thimerosal now would mean depriving people of protection against a whole host of dangerous illnesses. “That condition is going to cause kids in the developing world to die,” Bruce Gellin, the former president of Global Immunization at the Sabin Vaccine Institute, told me. Gavi has already begun the process of transitioning to some newer, thimerosal-free alternative immunizations, Berkley said. But such switches would come with costs—and the holdup in payment from the U.S. “has hampered and slowed down these efforts,” a Gavi spokesperson wrote over email.Gavi’s funding shortfalls will hold back immunization in other ways, too. In recent years, the organization has helped several nations roll out vaccines against HPV and malaria, with more introductions planned by 2030. But those plans are fracturing. Kate O’Brien, the director of the WHO’s Department of Immunization, Vaccines and Biologicals, told me she worries especially about the malaria program, which is now confronting a nearly 30 percent budget deficit. Essentially, that means that Gavi can support the number of doses that will cover only about 70 percent of its targeted moderate- and high-transmission malaria regions, O’Brien said—calling for “some really tough decisions.” She added: “Who are the 30 percent of communities that are actually not going to get this vaccine?” (The Gavi spokesperson said the funding cuts would limit the potential of malaria vaccination efforts and that, more generally, reductions in funding risk depleting vaccine stockpiles for a number of deadly infectious diseases and diminished the organization’s capacity for preventing outbreaks.)Global vaccination was already on shaky ground. Emergency conditions at the height of the coronavirus pandemic disrupted supply chains and health-care delivery, which impeded access to routine vaccinations and set the conditions for major outbreaks of diseases such as diphtheria. In many parts of the world, countries still have not returned to their pre-COVID immunization baseline, Anita Shet, a pediatrician and an infectious-diseases researcher at Johns Hopkins’ Bloomberg School of Public Health, told me. As funding shrinks, communities in hard-to-reach regions, where immunizing children is more expensive to begin with, may inadvertently lose out, exacerbating existing health disparities. Within the U.S., where health care is privatized, vaccine access for low-income and rural families is already wobbling: The paring-back of the national immunization schedule has prompted insurers and states to reconsider which vaccines to cover, and the Vaccines for Children Program, which covers underinsured kids, depends on an expert vaccine panel that the Trump administration’s decisions have rendered nonfunctional.Many lower-income countries, particularly on the African continent, have been working to independently finance vaccination, so that they are “no longer reliant on donations from high-income countries,” Abdu Adamu, a vaccine-implementation researcher based in Nigeria, told me. And in some ways, the abruptness with which American leaders have rescinded their support serves to only further motivate those efforts. But countries cannot instantaneously achieve immune sovereignty—and part of the tragedy here is how quickly the U.S. is undoing years of work. “We’ve made so much progress in the past 20 years, to bring low- and middle-income countries closer to where high-income countries are in terms of access to vaccines,” Chizoba Wonodi, a global vaccination expert at the Bloomberg School of Public Health, told me. A regression could happen much more rapidly, and then take far longer to recover from.In the meantime, the U.S.’s retreat from global vaccination could set this country back, too. Whatever infectious diseases spread more widely abroad could cross borders to threaten Americans, especially as vaccination rates here continue to waver and dip. Vaccine manufacturers facing resistance here could take their business elsewhere, putting other wealthy nations first in line to receive novel vaccines, Gellin said. Global well-being depends intimately on cooperation and trust. And when infectious threats inevitably crop up in the future, other countries won’t soon forget how quickly U.S. leaders broke their commitment to public health.