The Story Behind the Coronavirus ‘Flatten the Curve’ Chart

Mark Wilson, Fast Company:

The first instance of Flatten the Curve can be found in a paper called Interim pre-pandemic planning guidance: community strategy for pandemic influenza mitigation in the United States: early, targeted, layered use of nonpharmaceutical interventions, and no, it doesn’t exactly roll off the tongue. Published in 2007 by the CDC, the paper was a preview to a pandemic like COVID-19, and it suggested simple interventions like social distancing and keeping kids home from school in order to slow the spread of a disease so that the healthcare system could keep up.

On page 18, a graphic appears called Goals of Community Mitigation. No one I’ve talked to at the CDC can remember who made it, but the image is the root of Flatten the Curve as it appears today. Rendered in purple, it presents those two familiar curves with three numbered goals: 1. Delay outbreak peak 2. Decompress peak burden on hospitals/infrastructure 3. Diminish overall cases and health impacts. These curves don’t appear to be rooted in hard, literal data. Rather, they are illustrative of the exponential spread of pandemics, and how we might impact their speed of growth. In 2017, when the paper was updated, the graphic lost its 1, 2, 3 numbering scheme. In 2020, the graph’s colors were changed from purple to blue and orange. Otherwise, it remained mostly unchanged.

“I thought it was a beautifully clear and simple illustration of an important concept, but I had no idea that it would end up causing such a stir on Twitter and elsewhere,” says Rosamund Pearce, a data visualization journalist at The Economist. Pearce first heard about the graphic from her colleague Slavea Chankova, and she decided to rebuild it for a piece the pair was working on about COVID-19 for The Economist.

I first saw this illustration in that Economist article that popularized the term, but much deserved credit goes to the CDC for creating such a brilliant piece of design.