-- COVID-19 was likely in the United States as early as mid-December 2019, weeks before the virus was first identified in China.

-- Growing evidence, such as the detection of the virus genome in waste water samples in March 12, 2019 in Spain, shows COVID-19 was circulating outside of China earlier than previously thought.

-- Virus source tracing is a serious scientific matter. Being the first to report the virus does not mean that the virus had its origin in the Chinese city of Wuhan.

-- Historically, the place where a virus was first reported has not often been that of its origin.

A man wearing a mask walks past some Christmas decorations in Paris, France, Nov. 18, 2020. (Xinhua/Gao Jing)

BEIJING/WASHINGTON, Dec. 2  -- A newly released study by the U.S. Centers for Disease Control and Prevention (CDC) found that COVID-19 was likely in the United States as early as mid-December 2019, weeks before the virus was first identified in China, boosting evidence suggesting that the coronavirus was spreading around the world earlier than previously known.

COVID-19 infections "may have been present in the U.S. in December 2019," about a month earlier than the first case was officially confirmed in the United States, the CDC scientists wrote after finding evidence of infection in 106 of 7,389 blood donations from residents in nine states across the country, according to a study published Monday online in the journal Clinical Infectious Diseases.