New studies suggest coronavirus (COVID-19) appeared in the U.S. as early as December 2019, weeks before cases were first recognised.
A report by Associated Press (AP), quoting some studies, noted that while some experts are skeptical, federal health officials are beginning to accept a timeline in which small numbers of COVID-19 infections may have occurred in the U.S.
These infections according to the studies were found in five U.S. states; Illinois, Massachusetts, Mississippi, Pennsylvania and Wisconsin.
Recall that coronavirus emerged in Wuhan, China in late 2019 while the first record of the virus in the U.S. was in a traveller who returned from Wuhan on January 15, 2020.
While CDC officials at first said the U.S. outbreak occurred from mid-January to early February, these research including the one by the CDC suggests infections occurred earlier.
The CDC-led study published in December 2020 suggested the virus infected some Americans as early as the middle of December 2019. This study analyzed 7,000 samples from American Red Cross blood donations.
Another recent study published on Tuesday June 15, 2021, by the journal Clinical Infectious Diseases and a team including researchers at the National Institutes of Health (NIH) analyzed blood samples from more than 24,000 people across the country.
This was collected in the first three months of 2020 as part of a long-term study called “All Of Us” seeking to track 1 million Americans over years to study health.
While it is difficult to distinguish antibodies that neutralize SARS-CoV-2, and the virus that causes COVID-19, from antibodies that fight other coronaviruses, researchers in both studies used multiple types of tests to minimize false positive results.
According to the AP, Natalie Thornburg, principal investigator of the CDC’s respiratory virus immunology team said the earlier cases were not widespread.
“There were probably very rare and sporadic cases here earlier than we were aware of. But it was not widespread and didn’t become widespread until late February”.