Community transmission of coronavirus likely began in late January or early February after a single importation from China, the Centers for Disease Control and Prevention (CDC) announced in a report Friday.
The agency’s director, Dr. Robert Redfield, told reporters that the virus was spreading at these times in Washington state and other Pacific Northwest areas, nearly a month before community spread was first detected in late February, according to CNN.
The CDC used syndromic surveillance of emergency department records to trace the spread, along with coronavirus testing specimens and analysis of genetic material from the virus in early cases, according to the report. The syndromic surveillance was based on emergency department records from counties affected early by the pandemic and didn’t show an increase in cases involving coronavirus-like symptoms before February 28. (RELATED: CDC Says Coronavirus Not Easily Spread Through Contaminated Surfaces)
“CDC’s findings published today in the MMWR suggest that the virus that causes Covid-19 was imported into the United States from China in late January, early February, and this importation caused limited community spread in the northwestern United States,” Redfield said Friday according to CNN.
There were also importations of the virus to the U.S. from Europe.
“The findings do show that in late February, early March, there were several importations of the virus from Europe to California and northeastern United States and possibly elsewhere,” Redfield said.
By late February into March, there were several importations of the virus from Europe into California, northeastern U.S., and possibly elsewhere.
There was no indication that the virus had been introduced earlier than these timeframes, in November or December of 2019, according to Dr. Jay Butler, deputy director for infectious diseases at the CDC, NBC News reported.
The CDC didn’t announce the first case of person-to-person transmission until January 30, when Redfield said at the time that the agency’s assessment found that the “immediate risk to the American public is low.”