It never really made sense to me that the powers that be would want to mass-exterminate their own sheeple who will vaccinate and get boosters on command. Don't get me wrong, I don't think TPTB care if any of their sheeple die from the vaccine but it makes more sense to me those who are in charge would rather get rid of the the unvaccinated folk because we aren't going to comply with their every whim. So I think the vaccine might be an antidote or neutralizer for the Delta variant or some other strain of disease which will be meant to cull the unvaccinated dissenters. Basically, COVID was/is the flu, but they spun a narrative that it was some new pandemic and used the opportunity to vaccinate their sheeple. Now the narrative shifts to the "pandemic of the unvaccinated" and folks like you and me will be the target of a legit bioweapon.
Tl;DR: Vaccinate the sheeple, exterminate the dissenters.
Plausible.
And then they will literally cover up the real pandemic as nothing when the real Covid (Not flu) starts killing a few hundreds every day.