Population Basics Part 2

Data and Metrics

PART 2 on population basics from Dr. Michal Engelman. In case you missed Part 1 in this Nerdy Guest miniseries, here it is!

Q: Ok, now I understand what a population (and even a sub-population!) is… but why does that matter for dealing with COVID-19?

Population scientists can’t predict which people will get COVID-19, but they can tell us which *groups* of people have higher rates of illness and death. And that turns out to be a powerful tool for improving public health.

Even when we think about populations, most people find thinking about the individuals in them most intuitive. So we hear a lot about how essential workers are more likely to be exposed to the coronavirus and how people with chronic conditions are at extra risk of dying from COVID-19.

“Essential workers” and “people with chronic conditions” are both examples of subpopulations.

But when we think about what to do about those subpopulations, we often revert back to individual-focused thinking. We ask each person with chronic conditions, and each essential worker, to change their behaviors (stay at home; wear protective gear; etc.).

And even when we act more collectively (e.g., pushing essential businesses to protect their workers better), we’re usually centering specific behaviors, and using individual-focused thinking.

A broader population perspective on the pandemic helps us highlight something different: how economic and racial inequities that long preceded the pandemic are shaping its overall impact in the United States. One might argue that racial and economic inequities are political problems, not strictly health problems. But the difficulty of disentangling social and health inequities underscores the fact that protecting the health of the public, like defining a population, requires both solid science and responsible politics.

Population-based strategies attempt to change the underlying conditions that allow diseases to fester in communities. One relevant example from the history of public health is the establishment of municipal sewage systems, which turned out to do more for preventing cholera outbreaks, and improving health in other ways, than any precautions individuals could have taken to avoid infection.

Population-based strategies are a way to remove entire groups from harm’s way. They benefit those people who are most vulnerable within the (sub)population, as well as those who are less at risk. This turns out to be a very effective way of improving public health. Sometimes, though, what most benefits the whole (sub)population offers little benefit to the average participating individual. It could even be perceived as a burden. The resistance we see to ordinances closing down bars and restaurants highlights the difficulty of individuals agreeing to act in the interest of the population’s health.

Realistically, dealing with the pandemic will continue to require action at both the individual and population levels. Yet pandemics, by definition, are a population health problem, and individual-based approaches on their own are not likely to suffice. To prevent illness on a mass scale, you need solutions on a mass scale. Population science gives us the tools for thinking and acting on that scale.

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