The worst possible and most catastrophic course of action would...

The worst possible and most catastrophic course of action would be letting covid 19 run uncontrolled, vaccines or not.
The reality of "herd immunity" is mass murder.

1. Plague of Justinian—No One Left to Die

Three of the deadliest pandemics in recorded history were caused by a single bacterium, Yersinia pestis, a fatal infection otherwise known as the plague.
The plague decimated Constantinople and spread like wildfire across Europe, Asia, North Africa and Arabia killing an estimated 30 to 50 million people, perhaps half of the world’s population.

“As to how the plague ended, the best guess is that the majority of people in a pandemic somehow survive, and those who survive have immunity.”

2. Black Death—The Invention of Quarantine

The plague never really went away, and when it returned 800 years later, it killed with reckless abandon. The Black Death, which hit Europe in 1347, claimed an astonishing 20 million lives in just four years.

Forward-thinking officials in Venetian-controlled port city of Ragusa decided to keep newly arrived sailors in isolation until they could prove they weren’t sick.

At first, sailors were held on their ships for 30 days, which became known in Venetian law as a trentino. As time went on, the Venetians increased the forced isolation to 40 days or a quarantino, the origin of the word quarantine and the start of its practice in the Western world.
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https://www.history.com/news/pandemics-end-plague-cholera-black-death-smallpox