At least seven people in five US states were infected with the novel coronavirus weeks before those states reported their first cases, a new government study showed.
More than 24,000 blood samples taken for a National Institutes of Health research program between Jan. 2 and March 18, 2020 were analyzed and seven participants reported antibodies against SARS-CoV-2, the virus that causes COVID-19.
The positive samples came from Illinois, Massachusetts, Mississippi, Pennsylvania and Wisconsin, the researchers said.