Back in late February, one of the attendees at an elite health-care conference in Boston unwittingly spread COVID-19 to their colleagues. In the following weeks, 99 conference guests tested positive. Now, one study has linked between 205,000 and 300,000 coronavirus cases around the world to the two-day event. The Biogen meeting was one of the earliest examples in the U.S. of what is now commonly known as a superspreader event. Jacob Lemieux, the lead author of the study published Thursday in the journal Science and reported by the Boston Globe, estimates that the conference is responsible for around 1.6 percent of all cases in the U.S. since the start of the pandemic. “If there is a public-health message here, it is that the conditions that enable these types of massive superspreading events to occur are still with us,” Lemieux told the newspaper.