Not sure of attenuation since according to the Wikipedia page they are now excluding asymptomatic infections from the statistics, which lowers the number of confirmed.

The Wikipedia page says:

"On 6 February, the Chinese National Health Commission started to change how cases were reported – asymptomatic carriers, who tested positive for the virus but did not show clinical symptoms, would no longer be included in the number of confirmed cases. This had the effect of reducing the total number of cases reported, but also meant that potentially contagious individuals were ignored in reports."