When Robert F. Kennedy Jr. was appointed secretary of health and human services, everyone knew he was capable of doing great damage.

He had a long history of indulging conspiracy theories, particularly when it came to vaccines. Already, his attempt to re-assess immunization schedules in the U.S. has outraged pediatricians. But his latest broadside against science, a decision to withdraw U.S. funding from the global vaccine alliance GAVI, may kill far more children than anything he has so far tried at home.

The Global Alliance for Vaccines and Immunization, designed in cooperation between the U.S. and U.K. governments, as well as philanthropic organizations — particularly Bill and Melinda Gates’ foundation — was set up in 2000. Its mandate has been to increase access to vaccines for children whose families cannot afford them, primarily in the Global South. GAVI could have done more, especially during the COVID-19 pandemic, but even so it is fair to describe it as one of the few great success stories for international collaboration in the past few decades.