The availability of safe, effective COVID vaccines less than a year into the pandemic marked a high point in the 300-year history of vaccination, seemingly heralding an age of protection against infectious diseases. Now, after backlash against public health interventions culminated in President-elect Donald Trump's nominating antivaccine activist Robert F. Kennedy Jr. to be the nation's top health official, health experts and vaccine advocates say a confluence of factors could cause renewed, deadly epidemics of measles, whooping cough, meningitis, or even polio.
