There were efforts to suppress information and to keep the public in the dark; these efforts clearly seem to have been perpetrated by officials with all orders of government throughout the country. As for the notification to the WHO, what wasn't shared (and may not have been widely understood) was the ability of COVID-19 (the SARS-like virus identified as the time) to be transmitted from person-to-person.

Let's not forget, as well, that the PRC propaganda has been playing up the actions of the authorities in Wuhan--including the local public security organs--to punish those, including the late Dr Li Wenliang--who had disseminated information about what the virus was doing to people. The reason? They had not been authorized to disseminate that information.

Sounds like a cover up to me (and to officials in Beijing, based on what they've been saying).