Leaked documents obtained by CNN show that the Chinese government significantly underreported the number of its coronavirus cases early in the pandemic.
Data from Chinese health agencies show that officials in Hubei province, where Wuhan is located, failed to report thousands of new daily cases.
For example, the country reported 2,478 new cases on February 10 but officials privately recorded 5,918 new cases.
The underreporting was partly linked to the delayed onset of symptoms. In March, Chinese officials reported that it took an average of 2.3 days between infection and noticeable symptoms.
But the country was still underreporting its numbers in March. Hubei reported 2,986 deaths by March 7 while officials privately put the death toll at 3,456.
No evidence effort was deliberate:
The report notes that there is no evidence that there was a concerted effort by Chinese officials to deliberately conceal the extent of its outbreak.
The documents show that the early stage of the pandemic was complicated by a severe flu outbreak in Hubei, which reported 20 times the number of influenza cases at it had the previous year.
The flu was identified in Wuhan in December, while the coronavirus appears to have been spreading since November.
The Trump administration has accused China of intentionally hiding data and letting the virus spread around the world.
The Department of Homeland Security said in May that Chinese officials "intentionally concealed the severity" of its outbreak in January and failed to report the highly contagious nature of the virus to the World Health Organization.
Chinese whistleblowers have also said they were prevented from reporting on the coronavirus in December.
Experts say China made “mistakes”:
"It was clear they did make mistakes -- and not just mistakes that happen when you're dealing with a novel virus -- also bureaucratic and politically-motivated errors in how they handled it," Yanzhong Huang, a senior fellow for global health at the Council on Foreign Relations, told CNN.
"These had global consequences,” he added. “You can never guarantee 100% transparency. It's not just about any intentional cover-up, you are also constrained with by technology and other issues with a novel virus. But even if they had been 100% transparent, that would not stop the Trump administration downplaying the seriousness of it. It would probably not have stopped this developing into a pandemic."