Flattening The Curve: It's All About Capacity

by Erica Mitchell | March 13 2020 | 1 Comment

Flatten the curve-01-01We deal with the seasonal flu each year, right? Between October and March of every year, millions get infected, tens of thousands develop critical complications, some of whom even die. Now imagine that everyone who was going to get the flu got infected during the same month, essentially all at once. The impact on healthcare and the economy would be stunning. That's what we are trying to avoid with the spread of COVID-19: We are trying to "flatten the curve."

With any epidemic, there is a predictable curve in infected patients over time. During the first few days, a few patients are infected. Those numbers swell to a peak at the height of the infection, and then taper down again. This is what it looks like.

Epidemic curve without mitigation-01
When epidemiologists speak of "flattening the curve," what they want to do is spread out the same number of cases of infection over a longer period of time, in order to be able to meet the health needs of patients without putting strain on the healthcare capacity.  We can achieve this by social separation, easy access to infection testing, enforcing quarantines, and hand hygiene. This is what a flattened curve looks like.
Epidemic curve with mitigation-01

Do they want to eliminate new infections? Of course! Containment of the diseases is ideal and means fewer people get sick. But even mitigating the disease can have a tremendous impact on patient outcomes, mostly because it means the healthcare system is not overwhelmed and finite resources are not depleted.

Let's return to our thought experiment with all seasonal flu patients becoming sick all at once, during the same month. Doctors, hospitals, and ICUs would become overcrowded practically overnight, straining our capacity for rooms, beds, ventilators, medicine, and caregivers. Thankfully we are able to mitigate the seasonal flu with a vaccine. Seasonal flu also is easier to mitigate because similar strains circulate each year, so we have some immunity built up. It is also not as contagious as COVID-19 and not as dangerous to those who become infected. The result is a season of flu spread out over 6 months, so our healthcare capacity is not overwhelmed.

The idea is to do our best to mitigate COVID-19, which has no vaccine, which is so new we don't have any built up immunity, and is more contagious and lethal than the flu. If we can spread the infections from COVID-19 out over a few months, that means that patients - with COVID-19, but also patients getting sick or injured just as they would at any time of the year - can actually get a bed, see a doctor, be placed on a ventilator, receive medication. Flattening the curve will save lives.

When our healthcare system is beyond capacity, the worst possible decisions have to be made: Who gets the last ventilator? Who gets sent home to make room in the ICU? Who gets the last medication, injection, IV bag? No one in today's world should ever have to make those decisions, especially when there are proven ways to avoid reaching overcapacity.

When it comes to hospital-associated infections, the kind we usually discuss in this blog, containment is the absolute, nonnegotiable objective. An outbreak at a hospital can and must be contained immediately. A hospital or system is a manageable population where interventions can be implemented and monitored rigorously. When you are dealing with an outbreak on a national or global scale, containment cannot be the only goal - mitigation has to be a top priority. It's just not physically possible to implement interventions that would be used in a closed system like a hospital. So mitigation - flattening the curve - becomes the most important and most effective way to save lives.

For more information on how to flatten the curve, please visit these incredible resources.

Flattening the Coronavirus Curve | New York Times

Why ‘flattening the curve’ may be the world’s best bet to slow the coronavirus | STAT

Coronavirus: Why You Must Act Now | Medium

Flattening the Curve for COVID-19: What Does It Mean and How Can You Help? | Michigan Health

Why Everything Is Closing For Coronavirus: It’s Called ‘Flattening The Curve’ | Forbes

Steps to Prevent Illness | CDC  

Coronavirus disease (COVID-19) advice for the public | World Health Organization