Think you had coronavirus in December? New federal study shoots down that myth
If you thought you had coronavirus in the fall, it was probably just the flu, according to a new federal study.
Claims that some Americans became infected with COVID-19 as early as November have circulated around the U.S. the past few months, the Associated Press reported. Those claims are now debunked by a study from the U.S. Centers for Disease Control and Prevention.
The CDC released the most recent Morbidity and Mortality Weekly Report, titled “Evidence for Limited Early Spread of COVID-19 Within the United States, January-February 2020,” this week. The study used “four lines of evidence” to determine when the coronavirus was introduced into the U.S. — syndromic surveillance, surveillance for acute SARS-CoV-2 infection, phylogenetic analysis and the analysis of “known cases in persons with no relevant travel history before February 26” — according to the CDC.
The study determined that “from January 21 through February 23, 2020, public health agencies detected 14 U.S. cases of coronavirus disease 2019 (COVID-19), all related to travel from China,” the study says. Here’s how they did it.
First line of evidence
“Syndromic surveillance” uses data provided by 4,000 health care facilities in 47 states and the District of Columbia to monitor increases in the number of patients complaining of “COVID-19-like illness,” such as fever, cough, shortness of breath or difficulty breathing, according to the study. Researchers in “14 counties with early community-acquired cases” found “no substantial increase” in patients with those symptoms among the data before Feb. 28, the study says.
Second line of evidence
Six states — Washington, Michigan, Pennsylvania, Tennessee, Texas and Wisconsin — retrospectively tested 11,000 samples “from patients with acute respiratory disease” for coronavirus starting Jan. 1, but found no positive results from any of the samples collected before Feb. 20, the CDC study says. The first positive result was found in a sample collected from Washington state on Feb. 21, according to the CDC.
Third line of evidence
Researchers analyzed genetic material from early coronavirus cases found in the Seattle area using a process called “phylogenetic analysis” to determine where the infections originated, the CDC says. The analysis found “that a single lineage of virus imported directly or indirectly from China began circulating in the United States between January 18 and February 9,” according to the CDC study.
Fourth line of evidence
Finally, the researchers used samples collected from two people from Santa Clara County, California, who died after becoming infected with coronavirus in early to mid-February, the study says. The first was a woman who became ill on Jan. 31 and died Feb. 6 and the second a man who died at home between Feb. 13 and Feb. 17, according to the CDC.
“Information from these diverse data sources suggests that limited community transmission of SARS-CoV-2 in the United States occurred between the latter half of January and the beginning of February, following an importation of SARS-CoV-2 from China,” the study says.
This story was originally published May 29, 2020 at 3:28 PM.