Researchers at UT just released their findings. They went back to throat swabs taken in Wuhan, China and Seattle, Washington weeks before those cities were locked down.
Those swabs were from people who thought they had the flu. They were taken from January in China and February and early March in Seattle.
The researchers found some of those suspected flu cases were actually positive for COVID-19. The findings indicate for every two cases of flu there was one case of coronavirus.
With that many cases, researchers now believe the first case in Seattle probably arrived around Christmas and they estimate at least a third of those undisclosed cases in the U.S. were in children.
The first case of coronavirus in Washington State was not reported until January 21.
The governor started shutting down schools by early March. At that time, the state reported close to 150 cases. UT researchers now believe that number was closer to 9,000 and they believe because so many of the cases were in children, whose symptoms tend to be milder, those cases went undetected.