Top US infectious disease expert Dr. Anthony Fauci has asked China to release the medical records of nine people whose sickness might provide essential clues into whether Covid-19 first emerged as the result of a lab leak. “I would like to see the medical records of the three people who are reported to have got sick in 2019. Did they really get sick, and if so, what did they get sick with?” Fauci said in a statement.

The origin of the virus is hotly disputed, with U. intelligence agencies still examining reports that researchers at a Chinese virology laboratory in Wuhan were seriously ill in 2019 a month before the first COVID-19 cases were reported.

However, Chinese scientists and officials have been rejecting the lab leak hypothesis, saying the virus could have been circulating in other regions before it hit Wuhan and might have even entered China through imported frozen food shipments or wildlife trading. However, Fauci continues to believe the virus was first transmitted to humans through animals, pointing out that even if the lab researchers did have Covid-19, they could have reduced the disease to get in touch with such a big population.