![Ng Han Guan FILE - Marion Koopmans, right, and Peter Ben Embarek, center, of the World Health Organization team say farewell to their Chinese counterpart Liang Wannian, left, after a WHO-China Joint Study Press Conference at the end of the WHO mission in Wuhan, China, on Feb. 9, 2021. The hunt for COVID-19 origins has gone dark in China. An AP investigation drawing on thousands of pages of undisclosed emails and documents and dozens of interviews found feuding officials and fear of blame ended meaningful Chinese and international efforts to trace the virus almost as soon as they began, despite years of public statements to the contrary. (AP Photo/Ng Han Guan, File)](https://mapi.associatedpress.com/v2/items/0694ac5e28544c98a1a66e7b723cecc6/preview/preview.jpg?s=680x)
FILE - Marion Koopmans, right, and Peter Ben Embarek, center, of the World Health Organization team say farewell to their Chinese counterpart Liang Wannian, left, after a WHO-China Joint Study Press Conference at the end of the WHO mission in Wuhan, China, on Feb. 9, 2021. The hunt for COVID-19 origins has gone dark in China. An AP investigation drawing on thousands of pages of undisclosed emails and documents and dozens of interviews found feuding officials and fear of blame ended meaningful Chinese and international efforts to trace the virus almost as soon as they began, despite years of public statements to the contrary. (AP Photo/Ng Han Guan, File)
![Ng Han Guan FILE - A volunteer looks out near a Chinese national flag during a farewell ceremony for the last group of medical workers who came from outside Wuhan to help the city during the coronavirus outbreak in Wuhan in central China's Hubei province on April 15, 2020. The hunt for COVID-19 origins has gone dark in China. An AP investigation drawing on thousands of pages of undisclosed emails and documents and dozens of interviews found feuding officials and fear of blame ended meaningful Chinese and international efforts to trace the virus almost as soon as they began, despite years of public statements to the contrary. (AP Photo/Ng Han Guan, File)](https://mapi.associatedpress.com/v2/items/f906ff9dd17948bb87226e8c3cced14e/preview/preview.jpg?s=680x)
FILE - A volunteer looks out near a Chinese national flag during a farewell ceremony for the last group of medical workers who came from outside Wuhan to help the city during the coronavirus outbreak in Wuhan in central China's Hubei province on April 15, 2020. The hunt for COVID-19 origins has gone dark in China. An AP investigation drawing on thousands of pages of undisclosed emails and documents and dozens of interviews found feuding officials and fear of blame ended meaningful Chinese and international efforts to trace the virus almost as soon as they began, despite years of public statements to the contrary. (AP Photo/Ng Han Guan, File)
![Ng Han Guan FILE - A policeman moves journalists back from a farewell event held for the last group of medical workers who came from outside Wuhan to help the city during the coronavirus outbreak in Wuhan in central China's Hubei province on April 15, 2020. The hunt for COVID-19 origins has gone dark in China. An AP investigation drawing on thousands of pages of undisclosed emails and documents and dozens of interviews found feuding officials and fear of blame ended meaningful Chinese and international efforts to trace the virus almost as soon as they began, despite years of public statements to the contrary. (AP Photo/Ng Han Guan, File)](https://mapi.associatedpress.com/v2/items/ba9dc4060cca40d8b9fb0100587580aa/preview/preview.jpg?s=680x)
FILE - A policeman moves journalists back from a farewell event held for the last group of medical workers who came from outside Wuhan to help the city during the coronavirus outbreak in Wuhan in central China's Hubei province on April 15, 2020. The hunt for COVID-19 origins has gone dark in China. An AP investigation drawing on thousands of pages of undisclosed emails and documents and dozens of interviews found feuding officials and fear of blame ended meaningful Chinese and international efforts to trace the virus almost as soon as they began, despite years of public statements to the contrary. (AP Photo/Ng Han Guan, File)