Patricia Callahan's ProPublica investigation argues Robert F. Kennedy Jr. is eroding both pillars of America's vaccination system — parents' trust and children's access — risking a return of preventable plagues like Hib, which left unvaccinated New York infants severely ill. It traces past resurgences in the Soviet Union, Japan and Nigeria, and reports a measles surge of more than 3,600 cases across 46 states, while HHS defends Kennedy's overhaul as rebuilding trust through open review.