How to stop coronavirus: Why ‘flattening the curve’ could be key to fighting Covid-19

A chart has shot around the world as people try to understand the scale and speed of the coronavirus outbreak – and our response to it.

The principle of "flattening the curve", as shown in the graphic, has been hailed as a central part of how to deal with the pandemic, and an important response to questions about how the strategy of delaying the spread can actually work.

The chart – and the idea it helps illustrate – are being hailed as a neat summary of why it is so important for people to take measures to try and slow the spread of coronavirus, even if it is not possible to stop it entirely.

It shows that there is an important value in trying to ensure that the disease cannot be passed on too quickly, and to too many people at one time, or it could overwhelm the limited resources that are available for fighting against it.

It shows the flaw in the argument made by some commentators that the disease should just be allowed to progress: sweeping through the community at the speed it naturally would, allowing the epidemic to get it over with. Doing so helps turn the curve into a spike, potentially overwhelming our resources and causing problems for health professionals and other trying to fight the disease.

By "flattening the curve", as it has come to be known, people may not be able to reduce the number of people who are infected with Covid-19. The principle is not concerned with how many people actually get the disease, over the long term.

Instead, it is about ensuring that a more limited number of people are dealing with having the disease at any given time. In fact, the outbreak might actually last longer as a consequence of abiding by the principle, and that in one way is the aim.

The graph demonstrating the principle that has flown around the world shows a long-held principle shot around the world after it was shared by Drew Harris, a population health analyst at Thomas Jefferson University in Philadelphia. He took a graphic originally created by journalist Rosamund Pearce, who had been inspired by another chart in a CDC paper.

Harris drew a dotted line onto the chart, showing that the smoothness of the curve could be the difference between treating the disease and healthcare providers becoming overwhelmed.

"The ideal goal in fighting an epidemic or pandemic is to completely halt the spread. But merely slowing it – mitigation – is critical," explained Harris to The New York Times, when he was interviewed after the graph took off on social media.

"This reduces the number of cases that are active at any given time, which in turn gives doctors, hospitals, police, schools and vaccine-manufacturers time to prepare and respond, without becoming overwhelmed. Most hospitals can function with 10 percent reduction in staff, but not with half their people out at once."

Other versions of the same graphic have now been created and themselves been shared widely around the internet. One especially popular animation showed how the difference between a sharp and smooth outbreak could partly be the result of people's responses: that a lax attitude towards advice such as handwashing and social isolation could help push the curve upwards into dangerous territory.

It suggests that the simple precautions people have been advised to take – frequent hand-washing, catching coughs and sneezes in tissues, preparing for self-isolation and using health resources smartly – could be vitally important, even if they seem only to be postponing the inevitable.

The idea of flattening the curve has become part of official response ot the spread of the disease, and it appears to have proven useful.

After the first cases were reported in China, for instance, the government instituted a policy of putting infected cities into significant lockdown. The policy was initially questioned, but cases have slowed rapidly and healthcare providers appear to be more able to help those infected.