The emergence of SARS-CoV-2 in Europe and North America

TLDR

Accurate understanding of the global spread of emerging viruses is critical for public health responses and for anticipating and preventing future outbreaks. Here we elucidate when, where, and how the earliest sustained SARS‑CoV‑2 transmission networks became established in Europe and North America. Our analyses show that rapid early interventions prevented initial introductions in Germany and the United States, while later introductions from China to Italy and Washington established the earliest sustained transmission networks, demonstrating the effectiveness of public health measures and that intensive testing and contact tracing could have stopped outbreaks from becoming established.

Abstract

Accurate understanding of the global spread of emerging viruses is critical for public health responses and for anticipating and preventing future outbreaks. Here we elucidate when, where, and how the earliest sustained severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission networks became established in Europe and North America. Our results suggest that rapid early interventions successfully prevented early introductions of the virus from taking hold in Germany and the United States. Other, later introductions of the virus from China to both Italy and Washington state, United States, founded the earliest sustained European and North America transmission networks. Our analyses demonstrate the effectiveness of public health measures in preventing onward transmission and show that intensive testing and contact tracing could have prevented SARS-CoV-2 outbreaks from becoming established in these regions.