That's already been established. Many cases are asymptomatic or present mild symptoms that won't motivate the ill to seek out a test. Testing by country, state (province, etc.), and even region varies wildly.
right, i'm not making a new claim. i'm saying, that's one of the few conclusions we can draw from this data. it doesn't say anything about e.g. catching covid at the hospital, whether existing data on health consequences and mortality is less relevant, or that "covid is mild / just a flu" as some people seem to be concluding.
This was apparent last year from serologic antibody testing. The prevalence of antibodies was anywhere between 2-10x what we were finding in the tests, which made it pretty obvious that way more people had mild COVID than is being reported. Unfortunately, if someone picks up a runny nose and mild cold-like symptoms and then recovers, it doesn't make the news. But if you have a one-in-a-million freak case where a 25 year old ends up in the hospital testing positive, it gets plastered on every news publication and is repeated ad-nauseam even though it is a misrepresentation.
Well, yeah, but we knew that already. The UK has been monitoring the actual number of people infected with Covid via random sampling of the population for well over a year and it's always been rather higher than the detected cases, despite having a lot more mass testing than other countries.