This is not the Chinese making it up though. They are quoting what Dr. Giuseppe Remuzzi - a respected medical expert and Italy's leading clinical researcher - said during an interview with the NPR (American media) originally.
"And it's now emerging that the virus had been spreading for months before it was detective. I talked to Dr. Giuseppe Remuzzi, who's been talking to family doctors. They told him they saw cases that looked like severe pneumonia already last November and December. That's before the world even became aware of the COVID-19 outbreak in China.
GIUSEPPE REMUZZI: That they remember having seen very strange pneumonias, very severe, particularly in old people, in December and even in November. It means that the virus was circulating at least in Lombardy before we were aware of this outbreak occurring in China."
https://www.npr.org/2020/03/20/818797687/morning-news-brief
https://www.npr.org/2020/03/19/817974987/every-single-individual-must-stay-home-italy-s-coronavirus-deaths-pass-china-s
It's also not the only source and not the first time it's suggested either. Phylogenetic analysis shows the same thing and it seems to be widely agreed upon in the medical circles in Italy. This is what Maria Rita Gismondo, Italy's virologist from Sacco di Milano hospital said in an Italian interview in early March:
"Is it true that the virus had already arrived in Italy in November last year and therefore before the first atypical cases of pneumonia were discovered in China?
"This is well established, it clearly emerges from our studies at the University of Milan and from those of other groups of scientists."
How was it possible to trace the presence of the virus before it was discovered?
“These studies are based on genotyping, which is the photograph of the core of the virus. The comparison with the viruses circulated in China and in the rest of the world has made us understand that it is a single virus. We have genotyped many of them, starting the mapping of the virus path in Italy: from here we discovered that it was already present in our country since November last year, giving an explanation to many atypical cases of pneumonia "."
https://www.lanazione.it/firenze/cronaca/coronavirus-virologa-gismondo-1.5062536
It is not claiming that Italy is the source by the way; it suggests that the virus - regardless of its real origin - has most likely been circulating undetectable for much longer than first thought and then likely mutated into a much aggressive strain we're dealing with now.
The Chinese definitely were complacent and made mistakes (local authorities silencing doctors who were first reporting it and not taking them seriously) and very likely weren't completely transparent for sure - but the leaders of other countries are equally to blame; in fact even more so - they knew about the existence of the new virus since the end of December and took absolutely no action to do anything about it while the Chinese were already quarantining millions of people in its cities. In fact many still don't do anything about it so go figure... They took it even less serious than the Chinese authorities at the start so I don't get it why people are not blaming their local authorities if they so badly need someone to blame for the situation we all find ourselves in at this moment. Pointing the finger at someone is absolutely not a top priority but I guess it makes people feel better about themselves and their own lack of action (not directed at you personally haha).
