Trump quietly closed the U.S.'s vaccine safety office last year. Researchers are scrambling to replace it. - Yahoo News

Before the late 1980s, vaccine safety relied on parents, doctors, vaccine makers, and hospitals to step forward and report symptoms they feared were connected to a vaccine.

The Centers for Disease Control and Prevention then worked out a new system that sought out clusters of symptoms among people who receive a vaccine, and expanded that oversight during the H1N1 epidemic of 2009.

figure out which symptoms actually popped up long after a vaccine was injected, and which were just coincidental.

But in 2019, the National Vaccine Program Office was shut down in an effort to cut costs and "eliminate program redundancies," Health and Human Services Secretary Alex Azar wrote at the time.