COVID-19 may have been present in the U.S. in December 2019, weeks earlier than previously thought

The first case of COVID-19 in the United States was reported on January 19, 2020, when a person returned from China. According to a study published on Nov. 30 in the journal Clinical Infectious Diseases, the arrival of the novel coronavirus responsible for the COVID-19 pandemic may have been in the U.S. weeks earlier than previously thought. In the study, the Centers for Disease Control and Prevention analyzed American Red Cross blood donations for SARS-CoV-2 antibodies between Dec. 13, 2019, and Jan. 17, 2020, and found evidence of the virus in 1.1% of blood donations. It should be noted, however, that the presence of the virus in the U.S. at the time does not mean it was spreading throughout any local community in the United States.

As reported by Madison Dapcevich in Snopes...

While the findings suggested that the virus may have been present in the U.S. much earlier than previously believed, it is not possible to know whether the infection was spread through the community or associated with travel.

“It is not possible to determine whether the potential SARS-CoV-2 infections suggested by this study may have been community or travel-associated,” said Dr. Susan Stramer, vice president of Scientific Affairs at the American Red Cross, in a news release. “A previous survey of blood donors, conducted to help understand travel practices, determined that less than 3% of respondents reported travel outside of the U.S. within the 28 days prior to donation, and of those reporting travel, only 5% traveled to Asia.

Though the tests were looking for SARS-CoV-2 antibodies specifically, there are seven known types of other coronaviruses that have some similarities, so it is possible a level of cross-reactivity occurred. According to the Virginia Department of Health, most people become infected with coronaviruses that cause the common cold at some point during their lives. And because the blood samples were anonymous to researchers, none could be considered “true positives” — this can only be determined from a person who had received a positive molecular diagnostic test.

Furthermore, donations may also not represent all blood donors or donations in these states, so they cannot be used to generalize all blood donors during the dates in the report and cannot make an inference on national or state levels of infection rates during the study period.