I got absolutely royally fucked up by influenza and "sicker than I've ever been in my adult life" -- and I'm 49 -- but it was Jan 2019 not Dec 2019, so I'm pretty certain it wasn't COVID.
Probably 5% of the population every winter gets "sicker than they've ever been in their adult life" with some horrible influenza/bronchitis/pneumonia.
If everyone who got "sicker than they've ever been" in Dec 2019 were actually sick with COVID then January would have decimated long term care facilities around the United States. Instead you can't see any upward trend in excess mortality in Jan. If anything Jan and Feb were slightly low and the trend doesn't become apparent until late March.
My guess is now they know what it was.
https://www.cdc.gov/flu/professionals/diagnosis/clinician_gu...
There's also a lot of other cold and flu viruses other than influenza, and just a normal rhinhovirus cold virus can cause bronchitis or pneumonia.
If you had extensive direct contact with someone COVID positive and didn't take precautions then you just got kind of lucky. You weren't immune.
Which is why talking in absolutes makes you sound less credible, not more.
Meanwhile there was also an unusually bad flu going around at the same time affecting a high single digit percentage of the population. So ok it’s not impossible you caught COVID. There is a small but real chance, but it’s probably tens or even hundreds of thousands to one against.
I suspect it was the flu though. My desk neighbour at work was hospitalised for the flu (tested and confirmed) a week earlier. I had been vaccinated, but it's mayve the case I had a more mild case than he did thanks to the vaccination.
That being said, my partner is a nurse and was the only person in her department not to get covid. WE did get tested for covid antibodies in late 2020 and didn't have any, but it's possible they had diminished by then if it really was covid.
But the simplest explanation is still that it was just the flu.
His wife was still suffering side effects months later. Their grade school aged son had a fever for a couple of days.