New research has poured cold water on the theory that the Covid-19 outbreak in Washington state — the country’s first — was triggered by the very first confirmed case of the infection in the country. Instead, it suggests the person who ignited the first chain of sustained transmission in the United States probably returned to the country in mid-February, a month later. The work adds to evidence that the United States missed opportunities to stop the SARS-CoV-2 virus from taking root in this country — and that those opportunities persisted for longer than has been recognized up until now.