BOSTON (AP) — As many as 300,000 COVID-19 cases around the world can be traced to a two-day biotech meeting at a hotel in downtown Boston last February, according to a study published by the journal Science.

The meeting of Biogen managers sent 100 people home with the coronavirus who then spread it to 29 states and overseas to Australia, Slovakia and Sweden, according to the study published Thursday.

The study estimates the conference is responsible for about 1.6% of all cases in the United States.

The study was done by tracking the unique genetic signatures of the virus that could be traced to the Boston event.

The lead author was Jacob Lemieux, an infectious disease physician at Massachusetts General Hospital, but more than 50 researchers were credited.

“If there is a public health message here, it is that the conditions that enable these types of massive super-spreading events to occur are still with us,” Lemieux told The Boston Globe. “They’re still possible if we let our guard down. They’re still possible if infected but otherwise healthy people mingle and travel without restriction.”

Biogen in a statement said the pandemic has had a “very direct and personal impact" on the company and hoped that the study would “continue to drive a better understanding of the transmission of this virus and efforts to address it.”