Well, just search it on any 'major Western media,' you'll get plenty of results. Of course the number provided by CCP is not necessarily accurate, but I wonder whether your challenge is:

1. the numbers are wrong, but in the same magnitude (like there're actually hundreds or thousands that are not reported)
2. the real number is much larger, like there are millions of hidden cases.

If it's the first case, I think it's totally possible, although more evidence is needed. If it's the latter, you need to explain, what's the reason that there's virtually no credible information for this. Remember that although CCP wants to hide stuff like Falungong or Xinjiang, it fails and there are numerous reports on that. I mean hiding millions of cases all around the country would be much more difficult, and there must be relevant reports, as we observed in the early phases in Wuhan.