Submitting a VAERS report is an onerous duty that many just procrastinate about or ignore..
While there is, of course, a period of time after any vaccination during which you have not yet produced anti-bodies sufficient to mitigate infection the silly idea that you are not considered vaccinated until such time period has passed is an obvious ploy to keep the number of VAERS reports down.
i.e. Keel over dead of a stroke on the way home from getting the jab and you are not considered a vaccine-related casualty.
The truth is that no numbers on covid can be trusted as they’ve fudged them since day one. I personally know of a gunshot death, a ladder fall death, a car accident and a blood alcohol death (0.55 when 0.08 is legal limit, so almost 7x that) all counted as covid deaths...and I haven’t even looked hard to find those.