The SARS-CoV-2 virus was seen to be circulating as early as December of 2019.
A recent study conducted by investigators from the National Institutes of Health has discovered evidence of COVID-19 infections in 5 states earlier than was initially reported.
The study builds upon findings from the Centers for Disease Control and Prevention (CDC) which suggested the virus was in the country as far back as December 2019.
Results from the study were published in the journal Clinical Infectious Diseases.
"This study allows us to uncover more information about the beginning of the U.S. epidemic and highlights the real-world value of longitudinal research in understanding dynamics of emerging diseases like COVID-19," Josh Denny, an author of the study said. "Our participants come from diverse communities across the U.S. and give generously of themselves to drive a wide range of biomedical discoveries, which are vital for informing public health strategies and preparedness."
For the study, the team of investigators worked with Quest Diagnostics, an American clinical laboratory, and tested over 24,000 blood samples for antibodies against SARS-CoV-2 from across all 50 states between January 2 and March 18 of 2020.
The team used 2 platforms, the Abbott Architect SARS-CoV-2 IgG ELISA and the EUROIMMUN SARS-CoV-2 ELISA (IgG), in order to minimize the amount of false positive tests.
Findings from the study demonstrated that some participants, including ones from Illinois and Massachusetts, tested positive for antibodies on January 7 and 8 of 2020, indicating that they were exposed at least 2 weeks earlier. This would mean that the virus was circulating in the country in at least mid-December.
The investigators did note some limitations, including that they did not know if the participants who tested positive became infected while travelling outside of their communities.
"Antibody testing of blood samples helps us better understand the spread of SARS-CoV-2 in the U.S. in the early days of the U.S. epidemic, when testing was restricted and public health officials could not see that the virus had already spread outside of recognized initial points of entry," Keri N. Althoff, lead author on the study said. “This study also demonstrates the importance of using multiple serology platforms, as recommended by the CDC."