In Homeland Security advises that they occur “when a single person infects a large number of other people, or when a gathering is linked to a large number of cases”.
“There’s no rule for when a cluster of cases is big enough to be called a superspreader event. But these are not instances of spread within one household. Instead, these are large clusters of cases where infection occurs in settings such as churches, restaurants or bars.”
“To prevent superspreader events, we need to better understand them, said Anne Rimoin, an infectious diseases expert at the University of California, Los Angeles.
“She has called for detailed contact tracing of the infections around President Donald Trump, including those who attended a Sept. 26 Rose Garden ceremony and indoor White House reception for Supreme Court nominee Judge Amy Coney Barrett.
“The timing of the event and the number of people infected suggests the possibility of superspreading, she said.”