COVID-19 Spread Undetected in U.S., Europe Earlier Than Believed, Study Shows, Offering Lessons for Future Outbreaks, Including Transmission of Omicron Variant

Local COVID-19 transmission was underway in California, New York, Florida, and Texas well before the first reported U.S. case in Washington state on Jan. 20, 2020, according to a new study published in Nature, which indicates the virus spread much earlier and faster in the United States and Europe than previously thought.

The authors, an international team of infectious disease transmission experts, including Ira Longini, Ph.D., a biostatistics professor at the University of Florida College of Public Health and Health Professions and College of Medicine, conclude that the narrowness of the initial COVID-19 testing criteria, along with limited surveillance and testing availability, allowed the virus to circulate undetected for weeks. Community transmission was likely in several areas in Europe and the U.S. by December 2019 and January 2020, they write, and by early March, only 1 to 3 in 100 infections were detected by surveillance systems.

Read more about COVID-19 Spread Undetected in U.S., Europe Earlier Than Believed, Study Shows, Offering Lessons for Future Outbreaks, Including Transmission of Omicron Variant.