Quantcast
Environmental News for a Healthier Planet and Life

Help Support EcoWatch

What’s the Difference Between Pandemic, Epidemic and Outbreak?

Health + Wellness
A volunteer from Blue Sky Rescue wears a protective suit as she fumigates and disinfects outside an area of a local bus station on March 7, 2020 in Beijing, China. Kevin Frayer / Getty Images

By Rebecca S.B. Fischer

The coronavirus is on everyone's minds. As an epidemiologist, I find it interesting to hear people using technical terms – like quarantine or super spreader or reproductive number – that my colleagues and I use in our work every day.


But I'm also hearing newscasters and neighbors alike mixing up three important words: outbreak, epidemic and pandemic.

Simply put, the difference between these three scenarios of disease spread is a matter of scale.

Outbreak

Small, but unusual.

By tracking diseases over time and geography, epidemiologists learn to predict how many cases of an illness should normally happen within a defined period of time, place and population. An outbreak is a noticeable, often small, increase over the expected number of cases.

Imagine an unusual spike in the number of children with diarrhea at a daycare. One or two sick kids might be normal in a typical week, but if 15 children in a daycare come down with diarrhea all at once, that is an outbreak.

When a new disease emerges, outbreaks are more noticeable since the anticipated number of illnesses caused by that disease was zero. An example is the cluster of pneumonia cases that sprung up unexpectedly among market-goers in Wuhan, China. Public health officials now know the spike in pneumonia cases there constituted an outbreak of a new type of coronavirus, now named SARS-CoV-2.

As soon as local health authorities detect an outbreak, they start an investigation to determine exactly who is affected and how many have the disease. They use that information to figure out how best to contain the outbreak and prevent additional illness.

Epidemic

Bigger and spreading.

An epidemic is an outbreak over a larger geographic area. When people in places outside of Wuhan began testing positive for infection with SARS-CoV-2 (which causes the disease known as COVID-19), epidemiologists knew the outbreak was spreading, a likely sign that containment efforts were insufficient or came too late. This was not unexpected, given that no treatment or vaccine is yet available. But widespread cases of COVID-19 across China meant that the Wuhan outbreak had grown to an epidemic.

Pandemic

International and out of control.

In the most classical sense, once an epidemic spreads to multiple countries or regions of the world, it is considered a pandemic. However, some epidemiologists classify a situation as a pandemic only once the disease is sustained in some of the newly affected regions through local transmission.

To illustrate, a sick traveler with COVID-19 who returns to the U.S. from China doesn't make a pandemic, but once they infect a few family members or friends, there's some debate. If new local outbreaks ensue, epidemiologists will agree that efforts to control global spread have failed and refer to the emerging situation as a pandemic.

Terms Are Political, Not Just Medical

Epidemiologists are principally concerned with preventing disease, which may be fundamentally different than the broader concerns of governments or international health organizations.

As of this writing, the World Health Organization classifies the risk of global COVID-19 spread as "very high," the highest level in their risk classification scheme and one step below an official pandemic declaration. This means that the WHO remains hopeful that, by taking aggressive steps now, containment of localized outbreaks may still be possible.

But I and other scientists and public health officials are already calling this a pandemic. The official numbers count an excess of 100,000 cases in almost 100 countries, and community spread has been documented in the U.S. and elsewhere. By the classical definition, it's a pandemic.

A formal declaration of COVID-19 or any other infectious disease as pandemic tells governments, agencies and aid organizations worldwide to shift efforts from containment to mitigation. It has economic, political and societal impacts on a global scale.

Formal declaration needn't incite fear or cause you to stockpile surgical masks. It doesn't mean the virus has become more infectious or more deadly, nor that your personal risk of getting the disease is greater. But it will be a historical event.

Reposted with permission from The Conversation.

EcoWatch Daily Newsletter

Hurricane Florence on Sept. 12, 2018. ESA / A.Gerst / CC BY-SA 2.0

The 2020 hurricane season is now expected to be the most active since at least the early 1980s, meteorologists at Colorado State University, a standard bearer for seasonal hurricane predictions, announced Wednesday.

Read More Show Less
The Qamutik cargo ship on July 28, 2020 in Canada's Nunavut province, where two ice caps have disappeared completely. Fiona Paton / Flickr

Three years ago, scientists predicted it would happen. Now, new NASA satellite imagery confirms it's true: two ice caps in Canada's Nunavut province have disappeared completely, providing more visual evidence of the rapid warming happening near the poles, as CTV News in Canada reported.

Read More Show Less
The European Commission launched a new Farm to Fork strategy in an effort to reduce the social and environmental impact of the European food system. European Environmental Agency / Flickr / CC by 2.0

By Katell Ané

The European Commission launched a new Farm to Fork strategy in an effort to reduce the social and environmental impact of the European food system. It is the newest strategy under the European Green Deal, setting sustainability targets for farmers, consumers, and policymakers.

Read More Show Less
President Trump signs an executive order regulating social media on May 28, 2020 in Washington, DC. Doug Mills-Pool / Getty Images

Facebook and Twitter removed posts by President Donald Trump and his campaign Wednesday for violating their policies against spreading false information about COVID-19.

Read More Show Less
Florida Fish and Wildlife Research Institute staff and volunteers try to help a stranded bottlenose dolphin in Cockroach Bay near Ruskin, Florida on Sept. 17, 2015. FWC Fish and Wildlife Research Institute

A new study gives a first look at the presence and potential effects of plastics and new forms of synthetic chemicals in stranded dolphins and whales along the coast of the southeastern U.S.

Read More Show Less
Smoke rises above wrecked buildings following a deadly explosion on Aug. 4, 2020 in Beirut, Lebanon. Marwan Tahtah / Getty Images

By Alexander Freund

Lebanese Prime Minister Hassan Diab says he believes Tuesday's explosion in Beirut could have been caused by large quantities of ammonium nitrate stored in the port.

Read More Show Less

Trending

Black Americans are dying from Covid-19 at more than twice the rate of white Americans, and at younger ages, partly due to poor diets that make bodies less resistant to the coronavirus. Mireya Acierto / Getty Images

By Michelle D. Holmes

Most Americans know about the Dietary Guidelines for Americans primarily through their colorful representations: the original food pyramid, which a few years ago morphed into MyPlate. The guidelines represent the government mothering us to choose the healthiest vegetables, grains, sources of protein, and desserts, and to eat them in the healthiest portions.

As innocuous as the food pyramid and MyPlate seem, they are actually a matter of life and death.

Read More Show Less