Authors:Trevor Bedford, PhD
The news of infections caused by a novel coronavirus, and the everyday use of the names SARS-CoV-2 and COVID-19, became widespread around February. But, the question of how long the virus had already been present in the United States before that time has remained unknown. Now, a team of researchers has reconstructed some of the early transmissions of the virus. By analyzing the genomic sequences of SARS-CoV-2 samples from infected patients in Washington State, they suggest that most early SARS-CoV-2 infections derive from a single introduction in late January or early February, sparking rapid community transmission of the virus that went undetected for several weeks before this community spread became evident.