When it was disclosed last spring that the coronavirus had stealthily infected 99 people after the Cambridge, Massachusetts, pharmaceutical company Biogen held a two-day conference in February, it helped add the term "superspreader” to the pandemic lexicon.

Little did anyone know how super the spread would actually become.

A new analysis of the Biogen event at a Boston hotel has concluded that the coronavirus strains loosed at the meeting have since migrated worldwide, infecting about 245,000 Americans — and potentially as many as 300,000 — by the end of October.