FAA sucks in general, I recently was involved in buying a bankrupt airline and launching a new one so I own 2,% of each - they're generally involved in approving the use of any internally developed or commercial-of-the-shelf software that's to be used in critical flight operations.
Somehow they approved for use a terrible piece of software developed by one guy in 2004 in a WYSIWYG/VB-esque language that's so uncommon I don't want this comment appearing at the top of the Google results for its name and doxing me... and getting anything new approved by them is an absolute nightmare so we're probably going to be using this absolute piece of shit to run not only the airline we bought that has a bunch of 10-15 seaters with cargo for short haul flights in a particular geographic area, but also for a fleet of 757s that are going to do trans-Pacific flights daily...
Nobody knows what's going on, the first time I had COVID I had no idea whatsoever and only knew from an antibody test in Jul 2020 during routine blood work when I requested it. Never bothered getting vaccinated since the nucleocapsid antibodies were still detectable at high levels in May 2021.
Then I had it again in Dec 2021 after the holidays, my brother-in-law had a positive test after feeling somewhat bad, I had a stuffy nose the day I was informed of that test and we were right next to each other for a few days during that time so I'm fairly sure it was probably COVID again. Then my fiance had it (confirmed with a PCR test at least) in mid-Feb 2022 and was fairly sick (3rd dose of Pfizer/BioNTech's product taken in early Jan) for about 2 days but I never got anything and we took 0 precautions against me getting it.
There's too many variables and there's definitely some genetic factors/how much viral load you were exposed to coming into play.