"The Persistent Immunities Amongst Autocrats"
As the sick spread over the world, there was more than a social distance among the wealthiest.
Among those in the nebulous range of power and authority, or those extremely wealthy; the sickness was of no concern.
They did not get sick. They need not be bothered with the health of medical staff or the availability of medical supplies.
People that caught the sickness and survived had anti-bodies. Available in the blood. Collected anti-bodies gave immunity or recovery.
In the places where power was concentrated, the people got sick. Those in power were immune by taking the anti-bodies by decree or bribe.
Some places even combined larger scale transfusions of 'young blood' to the autocrats.
It was simply a matter of keeping 'compatible' people in role of continuous donors.
In very bad situations, the donors would be purposefully re-infected to refresh the immunity.
Damage to the internal organs would catch up. A donor would die eventually.
So the wealthy kept a wide supply of donors.
[I am still optimistic enough to hope this is only disturbing fiction.]