Here's the sad truth about how pandemics end - AlterNet

Since the beginning of the pandemic, epidemiologists and public health specialists have been using mathematical models to forecast the future in an effort to curb the coronvirus's spread.

But infectious disease modeling is tricky.

Epidemiologists warn that “[m]odels are not crystal balls," and even sophisticated versions, like those that combine forecasts or use machine learning, can't necessarily reveal when the pandemic will end or how many people will die.

As a historian who studies disease and public health, I suggest that instead of looking forward for clues, you can look back to see what brought past outbreaks to a close – or didn't.

In the early days of the pandemic, many people hoped the coronavirus would simply fade away.

Others claimed that herd immunity would kick in once enough people had been infected.

A combination of public health efforts to contain and mitigate the pandemic – from rigorous testing and contact tracing to social distancing and wearing masks – have been proven to help.

Even if the pandemic is curbed in one part of the world, it will likely continue in other places, causing infections elsewhere.

Whether bacterial, viral or parasitic, virtually every disease pathogen that has affected people over the last several thousand years is still with us, because it is nearly impossible to fully eradicate them.

Mass vaccination campaigns led by the World Health Organization in the 1960s and 1970s were successful, and in 1980, smallpox was declared the first – and still, the only – human disease to be fully eradicated.

Transmitted via parasite, it's almost as old as humanity and still exacts a heavy disease burden today: There were about 228 million malaria cases and 405,000 deaths worldwide in 2018.

Research on the global burden of disease finds that annual mortality caused by infectious diseases – most of which occurs in the developing world – is nearly one-third of all deaths globally.

Today, in an age of global air travel, climate change and ecological disturbances, we are constantly exposed to the threat of emerging infectious diseases while continuing to suffer from much older diseases that remain alive and well.

Once added to the repertoire of pathogens that affect human societies, most infectious diseases are here to stay.

Perhaps no disease can help illustrate this point better than plague, the single most deadly infectious disease in human history.

For example, medieval Egypt could not fully recover from the lingering effects of the pandemic, which particularly devastated its agricultural sector.