When did SARS-CoV-2 become established in Europe and North America?
An interesting study by Worobey and others published in Science 10 September 2020 looks at the emergence of SARS-CoV-2 virus in both Europe and North America. They conclude that rapid early intervention successfully prevented early introductions of the virus into Germany and the United States. However, later introductions of the virus from China to both Italy and to Washington State founded the earliest sustained European and North American transmission networks. Their analyses demonstrated the effectiveness of public health measures in preventing onward transmission and showed that intensive testing and contact tracing could have prevented SARS-CoV-2 from ever becoming established.
They found that despite early successes in containment, SARS-CoV-2 eventually took hold in both Europe and North America during the first two months of 2020: First in Italy around the end of January, then in Washington State around the beginning of February, and followed by New York City later that month. Their analyses delineated when widespread community transmission was first established on both continents and clarified the period before SARS-CoV-2 establishment when contact tracing and isolation might have been most effective.
By delaying COVID-19 outbreaks by even a few weeks in the United States and Europe, the public health response to the crisis and a particularly impressive response in Germany to an early outbreak bought crucial time to prepare for the virus when it finally did arrive.