NIH study suggests coronavirus may have been in U.S. as early as December 2019 The Washington PostMore evidence suggests COVID-19 was in US by Christmas 2019 Yahoo NewsScientists Report Earliest Known Coronavirus Cases in Five US States The New York TimesNIH researchers find more evidence Covid was circulating in the US in December 2019 CNN Some Americans were infected with COVID in December 2019 AxiosView Full Coverage on Google News