Many accounts of plagues of the past conclude with mysterious vanishing. Since science based medicine did not exist, accounts of contemporary historians exhibit ignorance of mythic quality, of which the historians, biblical and secular, had not the slightest hint.

The terror of ancient plagues, coupled with complete ignorance of the causes, has persisted into the current. If you don’t know anything about epidemiology, the myths occupy a corner of your mind, to be dragged out when fear is great and critical thinking is weak.

(CNN) 90% of Americans have prayed for healing, study finds. You don’t have to deny yourself the emotional support of prayer, provided public health policy is based on science. Passover is a great story.

The knowledge vacuum  persisted until the advent of epidemiology, which became a rational field with the advent of Koch’s Postulates, a set of criteria required to prove that a microbe causes a disease.  With a little modification, and accommodation of exceptions and complications, the Postulates remain valid today.

In ancient times, there were only a few legitimate causes of plagues:

• The Gods were angry.
• Chastisement of the Devil.
• Bad vapors or waters. In ancient times, a lot of things smelled bad, and most water tasted bad.
• Passage from one person to another.

In a world without science, these  were complete explanations. The Postulates marked a transition; they were eagerly taken up by early epidemiologists, who in a mere half-century managed to discover why many of the historical plagues vanished without apparent cause.

Yet epidemiology, so rich and precise in describing epidemics after the fact, has  weak powers of prediction. This is why WHO couldn’t say COVID-19 would escape China. This is also why someone in a CNN video, asked why he was not wearing a mask, replied, “God will heal this country.” A stronger science would have left no room for this.

Epidemiology is almost totally divorced from biochemistry. The COVID-19 genome was sequenced in a week, but there was and is no way to use a genome for prediction without clinical experience. Epidemics, like elections, are mostly studied with statistics. This is not great news, but it has an upside. It means the policy maker can largely understand some things, such as:

• COVID-19 isn’t going to “mysteriously vanish” like plagues of yore. Hint: COVID doesn’t involve vermin.
• As time goes on, epidemic predictions become more accurate.
• Virulence varies from time-to-time and place-to-place. (Reuters) New coronavirus losing potency, top Italian doctor says.
• Like all viruses, COVID has no ability to think, yet has complex “strategies” to overcome the defenses of an infected person.
• How public health policy can actually influence the virulence of COVID.

Which of the above is most important to you?

To be continued shortly. And yes, hares and foxes will figure in the telling.