Sure, you can't be completely confident about the numbers. But it's not like they could hide a pandemic from the public. I know literally no one who has had covid here, neither friends or friends of friends. But from my smaller circle of friends/family abroad (I've been here a long time...) I know people who had covid, and among friends of friends I know of people who died.
My experience shouldn't convince anyone, but there are limits to the spread of the pandemic here where people would actually believe the low numbers.
The economic numbers are similar. I run a yoga studio in Shanghai as well as traveling around the country doing seminars. I know how much money I made last year. I also know how crowded the restaurants I eat at, etc. are. I know how many people I see on the airplanes with me when I travel. I have friends doing business around china and know what their experiences are. My girlfriend has a clothing brand and I know how much money she's been making this year. Everyone I know has had a pretty good year, with a few bumps here and there.
My experience and that of people I'm close to isn't conclusive of any particularly precise numbers, but it's not consistent with the economy falling apart. We all experienced problems when covid first hit and had a couple of bad months. There have been a few ups and downs when a case or two is reported in a particular place and suddenly people stop going out for a couple of weeks, or can't travel (I had to postpone a trip to Chengdu earlier this year for the reason), but again the negative bumps all seem to be correlated with the news of what's happening, so no real disconnect there.
When it comes to vaccination, again, everyone I know has been vaccinated. Even when I went to Qinghai, a very rural place and one of the poorest parts of China, earlier this year my guides had both been vaccinated, and this wasn't long after vaccination had begun.