Health authorities recommend staying home and avoiding crowds to help slow the spread of COVID-19.

Angela Lang/CNET

For the most up-to-date news and information about the coronavirus pandemic, visit the WHO website.

As efforts to stop the spread of COVID-19 escalate around the world, attention has turned to how individuals and communities can protect each other. The illness, caused by a newly-discovered coronavirus, has made its way across every continent, besides Antarctica. The advice from health authorities has been constant: Wash your hands and don’t touch your face. But more stringent measures are being suggested by medical experts, including increasing social distancing and restricting mass gatherings — in an attempt to “flatten the curve”. What does that mean?

You’ve likely heard the term “flattening the curve” (or its feline-based Twitter-sibling, #catteningthecurve) and seen the graphs shared widely on social media. The graphs contain two curves — the first tall and thin, like Mount Everest, and the second thick and flat, more like a speed bump. 


Adapted from CDC pre-pandemic guidelines.


The widely-shared graph has been adapted from the CDC’s pre-pandemic guidance for mitigating the spread of infectious disease, which was mostly recently revised in 2017, and shows the “epidemic curves” of two different pandemic scenarios.

The sharp curve denotes how a pandemic caused by an infectious disease — like COVID-19 — would spread through a community with no intervention strategies in place. Without mitigating the spread, cases would rise rapidly, peaking when the community is almost wholly infected, before dropping back down. The second curve is much flatter and denotes a pandemic scenario where there has been intervention. 

What’s most notable with the “flattening the curve” idea is the addition of a single dashed line to denote the capacity of public health systems. This addition appears to have been first added by Drew Harris, a population health analyst at Philadelphia’s Thomas Jefferson University and is adapted in the graph below.


Adapted from CDC pre-pandemic guidelines/Drew Harries (@drewaharris).


At present, many graphs in countries like the US, Italy and Australia are showing rapid growth in confirmed positive cases — their epidemic curves are beginning to look like the red curve. This is a worst-case scenario, and would overburden critical systems. But health authorities and governments are now adopting strategies and measures that will see nations look more like the yellow curve. Here’s why that is so important.

Why it’s important to flatten the curve

Flattening the curve is the idea communities and countries can delay the peak of the outbreak and thus relieve some of the stress on the healthcare system. 

As the epidemic curves show, intervention is critical in responding to a pandemic because it drives the number of cases down and frees up the healthcare system to deal with an outbreak. The CDC’s community mitigation strategy for COVID-19 outlines two major reasons for flattening the curve:

  1. To protect individuals at increased risk for severe illness, including older adults and persons of any age with underlying health conditions
  2. To ensure the safety of healthcare and critical infrastructure workforces  

The responsibility for slowing down new cases doesn’t fall just to the vulnerable or those infected with COVID-19, but extends to the wider community. 

Governments and health authorities are asking people to change their behaviors to prevent a spike in cases which would send admissions to hospitals skyrocketing and stretch resources thin.

Those resources are going to be critical in combating any extensive outbreaks. We’re already seeing the consequences of not flattening the curve fast enough in places like Italy, where hospitals are overwhelmed. Patients with severe disease and breathing difficulties require mechanical assistance from ventilators but, according to a report by the Financial Times, there is a lack of equipment in the country due to the huge influx of COVID-19 cases. Ventilators are scarce.

And it’s a problem not limited to Italy. The US may have to battle a shortage of ventilators if the outbreak reaches levels like those seen in Wuhan, China, according to NPR

The good news is such a reality can be avoided — but it will require some shifts in behavior in the short-term. 

What can you do to flatten the curve

No matter where you are in the world, everyone fulfills a critical role of the response to a COVID-19 outbreak. The two pieces of constant advice from health professionals that you should always remember to best protect yourself from being infected:

Now, more stringent protective measures are now required — and the early response by governments and industry has been telling. The US has announced closures across the nation, affecting barstheme parks and schools. In addition, many industries have been shaken by the spread of coronavirus and huge sporting bodies like the NBA, MLB and NHL have postponed seasons to stop unnecessary public gatherings.

Such efforts attempt to aid the practice of “social distancing” — an idea that’s gained as much traction as “flattening the curve” in recent weeks and is recommended by the WHO. Social distancing is a protective measure that attempts to reduce the close contact people have with each other during an epidemic. 

An incredible piece of data journalism by the Washington Post is perhaps the best display of how social distancing can help slow the spread of disease. The piece shows exactly what it means to increase social distancing and self-isolate and how those measures can reduce the overall load of infections. Limiting movements and contact with others to a minimum greatly reduces the ability for a disease to spread through the community. 

What does that mean for you? How should you navigate this new world of self-isolation and small gatherings? Should you go to bars? Restaurants? Weddings? The gym? Parties? BBQs?

The information coming through differs, depending on where you are in the world, so it’s important to refer to the relevant local health authorities for how to best maintain social distancing practices in this scenario. For instance, as of Sunday March 15, the US CDC recommends that large events and mass gatherings with 50 or more people be postponed across the United States. Australian authorities suggest gatherings of 500 should be cancelled. Countries like France and South Africa suggest gatherings of over 100 people be cancelled.

Officials and authorities have to balance a whole host of concerns outside of epidemiological concerns. However, medical experts are suggesting people stay home as much as possible. Even if you’re young and healthy and may not be severely affected by COVID-19, you should reduce contact with others. Perhaps one of the best resources for US-based users is by The Atlantic and explains the various different social situations one should look to avoid in the coming weeks. 

The measures currently being taken may seem extreme, but they are backed by hard data. Social distancing has helped save lives in the past — most notably during the 1918 flu pandemic. The lessons from that pandemic over a century ago are just as important today.