A study published Monday in the journal Clinical Infectious Diseases conducted by researchers with the Centers for Disease Control and Prevention suggests that the novel virus was present in the United States as early as mid-December 2019. The conclusion is based on blood donations from the Red Cross from nine states, including Washington, Oregon, California, Connecticut, Iowa, Massachusetts, Michigan, Rhode Island and Wisconsin.
The conclusion is based on blood donations from the Red Cross from nine states, including Washington, Oregon, California, Connecticut, Iowa, Massachusetts, Michigan, Rhode Island and Wisconsin.
世界各国都在为病毒溯源。
只有爆发地无源头可溯。
是啊，美国应该早点让WHO来调查