Pandemics past: What we can learn from threats to the human race

It is important that we not only combat pandemics, but learn from them. As George Santayana wrote, those who do not learn from history are doomed to repeat it.

Pandemics such as COVID-19 carry many lessons. They teach us a great deal about infectious microbes such as SARS-CoV-2, ways of reducing their transmission, and therapies and vaccines.

But not all the lessons of pandemics are medical, and in many respects four more broadly human lessons are just as important:

We tend to think of contemporary circumstances as unprecedented, but COVID-19 is neither humanity’s first nor worst pandemic. The great influenza pandemic of 1918, which afflicted as many as 500 million people, claimed about 50 million lives.

More recently, HIV/AIDS has infected about 75 million people, to date causing 33 million deaths. By comparison, about 41 million people have been diagnosed with COVID-19, with 1.2 million deaths.

In fact, pandemics have been a regular feature of human history, and there is even archaeological evidence of prehistoric pandemics.

Ancient Athens was famously ravaged by an epidemic during its 30-year war with Sparta, the plague of Justinian struck the Byzantine empire in the 6^th Century, and the 14^th Century Bubonic plague killed as many as one-third of Europeans. Some outbreaks were even man-made – for example, American settlers used diseases such as smallpox to decimate native populations.

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In most cases, what we call infectious disease is the product of at least two factors – infection by a disease-causing organism and the host’s immune response. It is thought that the flu pandemic of 1918 proved so deadly because it elicited what is sometimes called a “cytokine storm”, an excessive immune response that exacerbates the disease’s toll on victims.

Armed with the knowledge that the host immune response is an important factor in disease severity and death rates, physicians and public health experts can take steps to reduce harm. For example, malnutrition is an important cause of a deficient immune response, and this can be alleviated through diet and nutritional supplements. When excessive immune response is the culprit, immune modulating drugs such as steroids can be administered.

As case numbers climb, physicians, nurses, and hospitals can be overwhelmed. Emergency responders such as police and firefighters can be taken out of action. Business shutdowns and loss of employment disrupt livelihoods, and school closures deprive young people of opportunities to learn. Growing poverty rates wreak damage that ripples throughout society.

A key response is to ensure that the cure does not become worse than the disease. Some pandemics have produced catastrophic responses.

During the Black Death that swept through Europe in the 14^th Century, Jews and other minority groups were sometimes accused of poisoning wells and streams, leading to widespread persecution and even massacres. The unknown is scary, but it is important to resist the impulse to take out fear and frustration on scapegoats.

Isolation, quarantine, and social distancing all separate human beings from one another, and especially in the case of the elderly, the infirm, and the poor, such separation can easily spawn loneliness.

Prior to the pandemic, the former US surgeon general warned of an “epidemic of loneliness,” a life situation that increases premature death rates by one-third, equal in harm to smoking 15 cigarettes per day.

Fortunately, there are ways to stay in touch. While social media, telephones, and video conferencing cannot replace human contact, they do permit a high degree of social interaction. Because those most at risk for loneliness are the same people who are least likely to be able to utilise such resources, helping them stay connected provides others with an opportunity to make a difference. Assisting with grocery shopping or even simply calling to check in lets shut-ins know that we care.

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Pandemics are terrible events. Communities and whole societies are disrupted. Many people die. Even greater numbers fall ill, and some live with the sequelae – lingering medical effects, disrupted employment, and grief – for years.

Yet by understanding the kinds of harms pandemics inflict, we can reduce their toll. Moreover, we can not only sustain lives but in some ways even enrich them.

Recognising our shared vulnerability and interdependence can make us better citizens, neighbours, and human beings.