The Middle Ages was marked by two great outbreaks of the Black Death, also known as bubonic plague, also known by the scientific name of the bacteria that causes it, Yersinia pestis. The second is well known, breaking out in 1346 in the eastern Mediterranean, becoming established in western Europe in 1347, and spreading and killing people for the next several years. The first, much less well documented, had multiple outbreaks in western Europe in the second half of the sixth century. That it was the same disease has been proven by the analysis of DNA from mass burial sites from the sixth century, where Y. pestis is clearly found.
The fourteenth-century plague killed at least a third of the medieval European population, maybe half in some areas. Probably everybody caught at least a mild case. It was spread by fleas, that would bite an infected rat, then bite a person, passing on the bacteria. There was of course no vaccine. The medieval population developed "herd immunity," that is with everybody infected and either dying or recovering with enough natural immunity to fight it off, the disease more or less disappeared after five or six years.
But it was not gone for good. Over the next several centuries, it came back again (though never in such force) every generation or so, when a new generation had been born that had never been exposed. The best known of these outbreaks was the Great Plague of 1666 in southern England. In London it was stopped by the Great Fire, which by burning up a lot of rats and fleas slowed the disease way down. The last major outbreak was in 1894 and affected people globally for close to twenty years. As I have discussed earlier, the Black Death is still endemic in rodents (mostly ground squirrels) in the American southwest. Fortunately it can now be cured with antibiotics if caught early.
Some people now advocate just letting everybody catch Covid-19 to develop "herd immunity" rather than striving for a vaccine. Thinking about losing a third or more of the population in the process may change their minds.
It is not clear what proportion of the population of late antiquity was wiped out by the plague, but the records that do survive speak of a devastating impact. Along with three or four outbreaks of the plague in fifty years or so, there was a smallpox epidemic. Ah, good times. It is however clear that the plague spread along trade routes and from the cities to the countryside as people fled from the urban centers where the infection rate was extremely high, not realizing they were spreading the disease in the process.
One indication of how devastating the sixth-century plague was is the evidence, from things like tree rings and pollen analysis, that the seventh and eighth centuries saw much smaller rural populations in Europe than in previous centuries. And the cities shrank even more; in Arles for example the whole city moved into the old Roman amphitheater, building their houses on the rows of seats, and they all fit.
One might consider that the sixth-century plague really ended the Roman Empire (helped along by the seventh-century rise of Islam). The fourteenth-century plague changed a lot of aspects of society as well as killing off people. The basic optimism that had marked much of the Middle Ages was gone, and there was a new fixation on morbidity, taking the form in some cases of extreme piety, in other cases a careless "live for today" attitude.
What changes will come from the Covid-19 pandemic? One assumes there will be more than an increased willingness of companies to have white-collar workers "work from home."
© C. Dale Brittain 2021
For more on disease and health and other aspects of life in the Middle Ages, see my ebook, Positively Medieval, available from Amazon. Also available in paperback1