AUDIE CORNISH, HOST:
When Donald Trump was still in office and had a working Twitter account, just one tweet could change an entire news cycle. People who research disinformation, like Kate Starbird, know this all too well.
KATE STARBIRD: My advisor, Leysia Palen, at the University of Washington, was watching content about COVID-19 and just following the CDC account, just trying to, like, understand what the CDC account was going to do. And one day, Donald Trump retweeted three or four tweets from the CDC, and it literally broke her data collection.