FluNET is precisely why we know flu dropped so much, and hence the large chunk of people with respiratory symptoms have been COVID-19 or otherwise, but certainly not flu.
Also, username-bro.
None of that has changed in the era of COVID, although the pattern of who goes to clinic for what may have. If there were flu out there we'd be detecting it is the bottom line.
Indeed, most flu patients don’t even see a doctor.
So, at the outset, the flu stats are coming from a very specific category of patients: in-patients and people with great insurance who have the time and money to get tested for the flu (even though it won’t make a bit of difference what the test says as it’ll be over in a couple weeks anyway.)
This second-category may be skewing things.
The personality-type that has a ‘need’ to know whether they have the flu was instead focused on Covid. They’d have the sniffles, go through a drive-through Covid testing site, get their negative result and breathe a sigh of relief. They would NOT however make an appointment with their doctor as they perhaps would have in years past as (a) they wanted to avoid sources of Covid, and (b) the doctors were discouraging appointments but for emergencies (and flu-like symptoms plus a negative Covid test, would not, in the patient’s mind, amount to an emergency.)
I doubt this explains all of the decrease in flu-positive tests. But, perhaps some of it.
And yes, we test for influenza a lot.
Before that it was noted that flu was killing more than coronavirus in summer.
The idea that the flu just 'disappeared' despite world trade continuing just sets off my bullshit detectors. Between all the countries that did little or nothing initially, and the people who refused to wear masks and didn't lock down...there's just no way it dropped to zero. Less? Sure. But gone? I simply don't believe it.