NEW YORK A meeting at a hotel in Boston last February may have ignited the spread of the pandemic virus to some 19,000 people in the area, a new study suggests. Health authorities had previously linked the meeting to more than 90 cases among people at the meeting and their contacts. But researchers found that a specific mutation in the virus from people associated with the meeting also showed up in hundreds of other cases, which allowed them to estimate the broader extent of the spread. She and co-authors began their analysis by deciphering the genetic makeup of the new coronavirus that was recovered from people sampled mostly in the Boston area between January and May. But the conference occurred before people in in the Boston area were taking steps to minimize the spread of COVID-19, she said.