Reading Time: 6 minutes

By Derek Ng,
Deborah Prabhu
and Allan Bonner

It seems as if everyone is an epidemiologist these days. So it’s worth considering epidemiology’s history and the role it should be playing in public policy, preventing disease and promoting health.

When U.S. President Donald Trump and reporters get into arguments about infections, testing and death rates, they’re engaging in an epidemiological discussion.

Not everyone who discusses disease and human health is qualified. But most of us are discussing, asking questions expressing concerns and offering opinions in this pandemic, including around the dinner table.

Derek Ng

Derek Ng

The term epidemiology was first used by Spanish physician Joaquin de Villalba in his 1802 work Epidemiología Española.

But the roots of this field are much older. In 400 BC, Hippocrates theorized that human ailments had a natural rather than supernatural cause, which was a helpful development for medicine and epidemiology.

This meant factors that caused disease could be measured, understood and possibly acted upon to alter the course of disease. Measuring and quantifying these factors held great promise to improve human health, so we could begin to understand who got sick, who died and why.

A major breakthrough for the field occurred in the mid-19th century – and this is a story told to all epidemiology students. A physician named John Snow demonstrated the power of properly enumerating the distribution of disease in the midst of a deadly cholera outbreak in London. He believed that contaminated water caused people to get sick.

To prove this, he visited houses and calculated how many cholera cases there were, cleverly mapped out these sicknesses and identified a water pump in the centre of the outbreak. Snow persuaded city officials to remove the handle of the water pump so no one could drink the water, and watched as the number of sick people dwindled.

Deborah Prabhu

Deborah Prabhu

This contains all the aspects of modern epidemiology: collecting data, determining the cause of disease and disease patterns, and implementing action to solve the outbreak. And Snow did this all without a computer or knowing the name or exact nature of the germ (the bacteria vibrio cholera).

And the scientific discipline was just getting started.

Epidemiologists have since made tremendous contributions to polio, sudden infant death syndrome, HIV/AIDS, cancer, cardiovascular disease, smoking and even automobile accidents, acts of violence and mental health, among countless others.

Technology is transforming epidemiology. Machine learning and artificial intelligence methods applied to population health give new insights. And the massive storage of health data from countries, counties and clinics provides tremendous opportunities for discovery.

But classical principles of study design, data collection, quality control and analysis remain pillars of all epidemiologic investigations.

There has always been a deep curiosity to know the cause and outcome of disease, with the intent to eventually intervene and alter the course of disease development. For researchers, it’s often easier to discover causes and identify high-risk populations than it is to intervene and change things.

Allan Booner on epidemiology


As German poet Johann Wolfgang von Goethe wrote: “knowing is not enough; we must apply … willing is not enough; we must do.”

At some point in the research, it becomes clear that stopping smoking is more important than knowing even more details about the dangers contained in cigarettes. As many smokers will tell you, learning about the dangers of smoking is far easier than quitting cigarettes for good.

So how do we go from quantifying health risks to developing preventive measures and treatments?

This huge undertaking requires a multi-disciplinary approach. University of California, San Francisco, professor of epidemiology and biostatistics Robert Hiatt, said that “epidemiology has a central role in team science, no matter what the health issue at hand.” Moyses Szklo, a professor of epidemiology at Johns Hopkins University, defined translational epidemiology as an “effective transfer of new knowledge from epidemiologic studies into the planning of population-wide and individual-level disease control programs and policies.”

For clinical research to be applied to population health, epidemiology should be involved in all phases, including the development of new interventions to implementing and evaluating those interventions.

It’s fair to say that the goals of translational epidemiology have not been fully realized. Knowing more doesn’t necessarily mean helping more. Knowledge needs to be applied in the real world to make a difference. Epidemiologists and health professionals can do better.

Researchers may publish in inaccessible or obscure journals, but that information doesn’t get into mainstream media or to the public. When the public does find out, there’s often conflicting information in various research papers and that confuses. Contradictory information is a natural consequence of the scientific discovery process, but we need to have conversations to explain what happened and why.

So it’s time to take the next step in science and epidemiology. That next step is a plain-speaking way to improve human health. It’s getting science out of labs and white coats and down to the street level where sick people are.

The good news is that we already know a lot about this pandemic. Treatments are improving as doctors and nurses get more skilled at managing COVID-19. Campaigns for safety, testing, isolating and tracing are largely well-received, and multiple vaccines are being developed at unprecedented speeds.

But this pandemic has also shown that there are challenges to improving human health other than the scientific ones. Funding was cut during the lull before this crisis. Necessary supplies weren’t stockpiled so we had a confusing public debate about wearing masks. For many issues and messages, there was little collaboration from governments, public and global health organizations and academics, which led to a lot of confusion and angst. And the public is wondering why it takes a year and a half to develop, test and distribute a vaccine.

So what’s the average person to do with all this information and even conflicting advice?

The lesson Snow’s actions taught and the purpose of translational epidemiology is to make good decisions and take precautionary actions, even when the details haven’t been fully worked out. John Snow didn’t have proof that the germ was in the water and he didn’t even know that the germ was bacteria, but he took action based on the information at hand.

Our job is to use our common sense, built upon generational knowledge about disease transmission, for good public health practices. Listen to the public health messages and think about reasonable ways to follow them. Deal with the ‘pump handles’ in our homes to disrupt the flow of the virus. We should spend our energy keeping ourselves and our loved ones safe.

We’ve known for a long time that washing hands is one of the best ways to reduce disease. We don’t need another study to prove this. We don’t need a debate about whether COVID-19 can live on fish, meat, eggs or plates. Cleanliness is its own reward. Children’s clothes, toys and the surfaces on which they play should also be clean.

We also don’t need a study to determine whether going to a crowded pub for two hours increases your risk of infection by 50 or 55 percent. These differences don’t matter – the danger does. Places and events with lots of people breathing, sneezing and talking on top of each other are simply risky.

We already know good safety practices from our grandmother – but are we courageous and persistent enough to follow them, for ourselves, our families and our communities?

More and new information on this virus is coming out daily. It’s interesting and sometimes helpful. But more information should not delay action right now. There’s lots we can do to keep families safe at home, in cars and in public while the debate is going on.

There’s no downside to cleanliness, keeping a distance, having a smaller social bubble, wearing a mask, and working on all the habits we already know promote good health.

Dr. Derek Ng, PhD, is an assistant professor in the Department of Epidemiology at the Johns Hopkins Bloomberg School of Public Health. Dr. Deborah Prabhu, MBBS, graduated as a physician and worked in medicine in India before moving to Toronto. Dr. Allan Bonner, MSc, DBA, is a crisis manager based in Toronto.

Derek, Deborah and Allan are Troy Media contributors. Why aren’t you?

© Troy Media


The views, opinions and positions expressed by columnists and contributors are the author’s alone. They do not inherently or expressly reflect the views, opinions and/or positions of our publication.