With the Flu, they look at Flu-like symptoms and many cases go unreported so the actual numbers of those infected with the Flu are logically higher than reported - but you're nuts if you think we've had 250M cases of the Flu in the US this year (and your math doesn't add up so you may have put in an extra zero) so I guess should stop here.....but
If you watch the Task Force briefings, you get some good info...right now, the original, really bad predictive models/numbers aren't adding up....by a long shot. The only way for some numbers to even approach some of the models (one model predicted 500K deaths in USA alone and had to be modified to a possible 20K) is if there are massive numbers of truly asymptomatic cases running around and now they are searching to see if those cases even exist and, if so, what the actual numbers may be....because none of the predictive models was worth beans and only served to cause panic...now, as true data comes in, the virus can still be deadly, but the picture is way rosier than it used to seem.