The cure to all ills

As the pandemic swept across the world, the race for a vaccine began.
Production lines came to life, gambling on various candidates so they’d be ready with supply.
Company after company released their testing results.
Many successes, with few or no side effects.
The government bought up the doses, and sent them out for distribution.
Hidden in the herd, a secret contractor’s product, which they allocated to prisons, soup kitchens, and welfare institutions.
While agents shredded records and smashed hard drives, the slow-acting toxin annihilated the so-called “undesirables.”
And the unsuspecting agents, too, for the truth had also become undesirable.