The United States government has reason to believe that several researchers inside the WIV became sick in autumn 2019, before the first identified case of the outbreak, with symptoms consistent with both COVID-19 and common seasonal illnesses. Ensuring a Transparent, Thorough Investigation of COVID-19’s Origin. 美國國務院. 2021-01-15 [2021-06-21]. (原始内容存档于2021-07-07) (英语).
The United States government has reason to believe that several researchers inside the WIV became sick in autumn 2019, before the first identified case of the outbreak, with symptoms consistent with both COVID-19 and common seasonal illnesses. Ensuring a Transparent, Thorough Investigation of COVID-19’s Origin. 美國國務院. 2021-01-15 [2021-06-21]. (原始内容存档于2021-07-07) (英语).