A new study says COVID-19 may have been present in Massachusetts as early as December 2019, according to the National Institutes of Health.
In a statement Tuesday, the NIH said its All of Us research program found evidence of COVID-19 infections in Massachusetts and four other states that occurred before the presence of the virus was confirmed in those jurisdictions.
Massachusetts officials publicly confirmed the first case of COVID-19 in a statement issued Feb. 1, 2020.
But according to the Tuesday statement from NIH, the disease had likely penetrated Massachusetts far sooner.
The NIH said researchers analyzed over 24,000 blood samples from study participants across the United States between Jan. 2 and March 18, 2020. Researchers detected antibodies against the virus in nine participants’ samples, according to the statement.
Those nine samples, NIH said, came as early as Jan. 7 from participants in Illinois, Massachusetts, Mississippi, Pennsylvania, and Wisconsin. Most positive samples were collected before the first reported cases in those states, according to the agency.
Antibodies, the NIH said, don’t appear until about two weeks post-infection, meaning study participants who had antibodies were exposed to COVID at least several weeks before their sample was taken.
In the study, the statement said, the first positive samples came from participants in Illinois and Massachusetts on Jan. 7 and 8, 2020, respectively, suggesting the virus was present in both states in late December of 2019.
“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,” said Dr. Josh Denny, chief executive of All of Us and an author of the study, in the NIH statement. “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.”
Dr. Keri N. Althoff, lead author of the study and an associate professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health, spoke to the critical importance of antibody testing in the statement.
“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,” Althoff said. “This study also demonstrates the importance of using multiple serology platforms, as recommended by the CDC.”