A new study has found that there were thousands of undetected early cases of COVID-19 at the beginning of this year and the disease was far more widespread in Wuhan, China, and Seattle in the US weeks ahead of lockdown measures in each city.
The first case of COVID-19 in Seattle may have arrived as far back as Christmas or New Year’s Day, concluded researchers from The University of Texas (UT) at Austin in the US.
“Even before we realized that COVID-19 was spreading, the data imply that there was at least one case of COVID-19 for every two cases of flu,” said Lauren Ancel Meyers, a professor at UT Austin.
“Since we knew how widespread flu was at that time, we could reasonably determine the prevalence of COVID-19,” Meyers said.
“Given that COVID-19 appears to be overwhelmingly mild in children, our high estimate for symptomatic pediatric cases in Seattle suggests that there may have been thousands more mild cases at the time,” said Zhanwei Du, a postdoctoral researcher in Meyers’ lab and first author on the study.
According to several other studies, about half of COVID-19 cases are asymptomatic, leading researchers to believe that there may have been thousands more infected people in Wuhan and Seattle before each city’s respective lockdown measures went into effect.
A study published in the journal EClinicalMedicine stated that around a third of the estimated undiagnosed cases in the US were among children.
“We can go back and piece together the history of this pandemic using a combination of investigative techniques and modeling,” Meyers said.
“This helps us understand how the pandemic spread so quickly around the globe and provides insight into what we may see in the coming weeks and months,” she said.