Currently about half of COVID-19 patients in hospitals are incidental cases who were admitted for another reason and then tested positive during admission screening.

https://gothamist.com/news/new-preliminary-state-data-shows-...

There are many people who have these numbers and study them.

Public health officials in the US have both the reported numbers as well as piggy backing on the system set up for influenza monitoring (CLI & ILI).

Simply because not all public reporting is as rich as, say, Illinois or Pennsylvania's, doesn't mean these figures aren't carefully scrutinized -- especially when threatened by political leaning from either side of aisle (such as when the then-current administration pressured the CDC to change and alter reports).

In my experience, hospital operations officers, health information exchanges, and, depending on the state, state HHS agencies don't mess around.

[0] https://www.cnbc.com/2021/04/09/trump-officials-bragged-abou...