Coronavirus began slowly spreading in the US as early as late January or early February — and went undetected for a month, according to the Centers for Disease Control and Prevention.
The federal study released Friday — the most comprehensive look yet as to when the virus that causes COVID-19 began spreading — found limited spread in some US communities between Jan. 18 and Feb. 9.
“As America begins to reopen, looking back at how COVID-19 made its way to the United States will contribute to a better understanding to prepare for the future,” CDC Director Dr. Robert Redfield said in a call with reporters, according to NBC News.
The study relied on four types of data. Researchers looked at reported illnesses by hospital emergency departments across the country and an examination of about 11,000 respiratory specimens collected in January and February. They also looked at genetic analysis of viruses taken from patients in California, Washington and the northeast and autopsy findings from California.
The first US infection to be identified was a Washington state man who became sick after returning to Wuhan on Jan. 15. He sought help from a clinic on Jan. 19.
Meanwhile, early instances of infection were found in the 11,000 airway samples taken from six states — the earliest collected Feb. 21 in the Seattle area.
The US’s ban on travelers from China began on Feb. 3.
The first non-travel related cases were confirmed on Feb. 26 in California and two days later in Washington State.
That was around the same time the virus began making its way into the US 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.
The virus did not spread in the US any earlier, in November or December, meaning anyone who believed they had coronavirus during this time likely had the flu.
Trevor Bedford, one of the report’s authors who has been tracking the pandemic using the virus’s genetic code, said there may have been a few undetected cases of coronavirus in the US in December or January — but the flu season was at its height.
“Based on just symptoms in January, it’s almost certainly flu or another respiratory infection,” Bedford told the Associated Press in an email.
A separate study released Friday provided clear evidence for multiple introductions of coronavirus infections, largely from Europe, into New York during the first weeks of March.
With Post wires
