The problem for the lab-leak position is that the U.S. has never had access to the Wuhan lab and has thus been unable to reach a definitive answer for more than five years. Now that the CIA has at last come to a conclusion, not all scientists are sold on what it has reported, seeing the results as thinly scientifically sourced.

Foreign ministry spokesman Mao Ning said the laboratory leak conclusion being extremely unlikely was reached by the China-WHO joint expert team based on field visits to relevant Wuhan laboratories.