On Jun. 4, 2020, data from the Broad Institute of MIT and Harvard, Massachusetts General Hospital, and the Massachusetts Department of Public Health provided insights into the entry of SARS-CoV-2 virus in the Boston area and epidemiological events that shaped the trajectory of the epidemic in the region. The first confirmed case of COVID-19 in Massachusetts, a traveler returning from Wuhan, China, was reported in early February.

Viral genomic data provided a more complex and detailed story of the pandemicﾒs arrival and spread across the city and the Commonwealth. No single event or importation alone was responsible for the ongoing spread of COVID-19 in the Boston area; rather, there were multiple entries within a few weeks, from both domestic and international sources.