The WHO says the new coronavirus is a pandemic. Here’s what that means

COVID-19’s rapid spread around the world has killed thousands, infected many more and triggered historic quarantine measures to keep the most vulnerable people safe. But it was only on Wednesday that the World Health Organization’s chief officially called it a pandemic. What does that designation mean in practice? Here’s what you need to know.

What ‘pandemic’ means

Open this photo in gallery:

Pandemic comes from the Greek words pan, “all,” and demos, “people.” Health agencies use it to refer to the worldwide spread of a previously unknown disease. But since there’s no globally accepted definition of “worldwide” – How many countries? How many continents? – a disease may sometimes be treated as a pandemic in one jurisdiction, but not another. Australia, for instance, effectively started treating the current coronavirus as a pandemic in February, when the World Health Organization hadn’t yet called it that.

The last generally agreed-upon pandemic was 2009′s spread of H1N1, also called swine flu. When WHO revised its guidelines for pandemics at the time, it didn’t include a single, quotable definition of what a pandemic is. Instead, it described six phases from initial infections to pandemic, each giving national health authorities advice about what to do as the urgency increased:

• 1: Animals are infected with a disease, but not humans.
• 2: Some humans are infected with the disease.
• 3. Small clusters of the disease have been reported, but not human-to-human transition.
• 4. Human-to-human transmission has been verified and is able to cause sustained community-level outbreaks.
• 5. The virus has caused sustained community-level outbreaks in two or more countries in one WHO region. This stage can also serve as a signal that a pandemic is imminent.
• 6. Additionally to 5, the disease has caused sustained outbreaks in at least one other country or WHO region. It’s only at this stage that it can be considered a pandemic.

Later revisions to the influenza guidelines simplified and blended these stages. First there’s an interpandemic phase between outbreaks of a disease; then an alert phase, when a new disease type is observed in humans; then a pandemic phase, when the disease has spread globally; and finally a transition phase, when the global risk subsides. WHO risk-management documents acknowledge that the situation can quickly change between the stages. Ultimately, the declaration of a pandemic is up to the WHO director-general, “based on risk assessment and appropriate to the situation.”

Director-general Tedros Adhanom Ghebreyesus declared a pandemic on March 11, by which point the coronavirus was in more than 110 countries. Dr. Tedros cited “alarming” increases in transmission and in government inaction, but denied that the new description changed the WHO’s assessment of the threat: “It doesn’t change what WHO is doing, and it doesn’t change what countries should do.”

Open this photo in gallery:

How is it different from an epidemic or outbreak?

An outbreak is the emergence of a disease in a particular place, while an epidemic is a dramatic, sudden or unexpected rise in infections within a country or region. When COVID-19 initially emerged in the Chinese city of Wuhan last December, that was an outbreak, but by the point where it had infected thousands in Hubei province and its environs, it was an epidemic. If a new disease becomes so established that there’s a baseline level that is considered normal, then it’s endemic: The common cold, for instance, is caused by other types of coronaviruses that nearly everybody has at some point. And if a disease is endemic but causes a sustained level of infection higher than health officials think it should be, it’s hyperendemic.

A key stage in the transition from outbreak to epidemic to pandemic is community spread, meaning the disease is present in patients who hadn’t recently travelled to an infected area and have had no known exposure to another infected person. In other words, once a country’s health officials can no longer keep track of where every case originates, it’s too late to completely stop it from reaching that country’s general population.

Open this photo in gallery:

Does ‘pandemic’ mean it’s deadlier?

Yes and no. “Pandemic” refers to where the disease has spread, not how many people it’s infected or how likely it is to kill people; theoretically, you could have a pandemic of a disease with a near-zero mortality rate. But with a potentially deadly virus, the spread and the death toll are interrelated. In the first two months after COVID-19 was discovered in China, health officials had a more or less clear idea of where the disease was likely to come from, which meant they could target their messages to people travelling from those places, averting infections and saving lives. But in a pandemic situation, the disease could be introduced to an uninfected population from lots of different places, making it harder to stop and more likely to infect the most at-risk groups: elderly people, patients with pre-existing medical conditions and health-care workers.

Where is COVID-19 now?

What are the symptoms of COVID-19?

COVID-19 is caused by a type of coronavirus, officially named SARS-CoV-2, that is in the same family of viruses as SARS and MERS. An infected person may feel feverish, have a dry cough or notice general aches. Some people are infected but don’t show any symptoms, and most recover from the virus without special treatment. Others may have the flu or another similar respiratory illness. If in doubt, there’s a test health officials can form to see if you have COVID-19; here’s the relevant contact information for health authorities in Canada.

HOW DOES CORONAVIRUS

INFECT A PERSON?

Human coronaviruses most commonly spread from an infected person to others through:

The air by coughing and sneezing

Close personal contact, such as touching or shaking hands

Touching the eyes, nose or mouth after touching an infected surface

Rarely, fecal contamination

WHAT ARE THE SYMPTOMS OF THE VIRUS?

Headache

Dry cough

Fever

In more severe cases, infection can cause pneumonia, severe acute respiratory syndrome, kidney failure and even death

SOME FACTS ABOUT THE VIRUS

Belongs to large family of viruses that cause illnesses ranging from common cold to more severe diseases such as MERS and SARS

Coronaviruses are zoonotic, meaning they are transmitted between animals and people

There are no specific treatments for coronaviruses, but symptoms can be treated

MURAT YÜKSELIR / THE GLOBE AND MAIL, SOURCE: Centers for Disease Control and Prevention, Health Canada, WHO

HOW DOES CORONAVIRUS INFECT A PERSON?

Human coronaviruses most commonly spread from an infected person to others through:

The air by coughing and sneezing

Close personal contact, such as touching or shaking hands

Touching the eyes, nose or mouth after touching an infected surface

Rarely, fecal contamination

WHAT ARE THE SYMPTOMS OF THE VIRUS?

Headache

Dry cough

Fever

In more severe cases, infection can cause pneumonia, severe acute respiratory syndrome, kidney failure and even death

SOME FACTS ABOUT THE VIRUS

Belongs to large family of viruses that cause illnesses ranging from common cold to more severe diseases such as MERS and SARS

Coronaviruses are zoonotic, meaning they are transmitted between animals and people

There are no specific treatments for coronaviruses, but symptoms can be treated

MURAT YÜKSELIR / THE GLOBE AND MAIL, SOURCE: Centers for Disease Control and Prevention, Health Canada, WHO

HOW DOES CORONAVIRUS INFECT A PERSON?

Human coronaviruses most commonly spread from an infected person to others through:

The air by coughing and sneezing

Close personal contact, such as touching or shaking hands

Touching the eyes, nose or mouth after touching an infected surface

Rarely, fecal

contamination

COMMON SIGNS OF INFECTION

Headache

In more severe cases, infection can cause pneumonia, severe acute respiratory syndrome, kidney failure and even death

Dry cough

Fever

SOME FACTS ABOUT THE VIRUS

Belongs to large family of viruses that cause illnesses ranging from common cold to more severe diseases such as MERS and SARS

Coronaviruses are zoonotic, meaning they are transmitted between animals and people

There are no specific treatments for coronaviruses, but symptoms can be treated

MURAT YÜKSELIR / THE GLOBE AND MAIL, SOURCE: Centers for Disease Control and Prevention, Health Canada, WHO

What do I do in a pandemic?

The most important things you can do are to maintain good hygiene (regular and thorough hand-washing, cleaning surfaces you touch often), practise physical distancing (avoiding contact with others unless absolutely necessary) even if you’re not sick, and self-isolate for 14 days if you do have COVID-19 symptoms or have just come back from overseas. All levels of government in Canada and other countries have been mobilizing in different ways to ensure people do these things. Here are some of the resources The Globe has compiled to help you through this pandemic.

I think I have symptoms of COVID-19. What should I do?

Overview: What you need to know about COVID-19

Your cleaning questions answered

Good foods and supplies to buy for staying at home

Full coverage: All coronavirus news stories, no paywall

When is the pandemic over?

The exact endpoint is debatable, but it’s up to the WHO director-general to say when the pandemic he declared is finished. Suffice to say, we’re not there yet. First the global population has to get through the so-called infection curve: An increase of new cases to their maximum, and then a decrease to a low and sustained level. Officials’ top priority is to make sure the peak of that curve doesn’t exceed their health-care systems’ capacity to care for patients, which is why everything you can do to stop infection matters.

For Canadian health-care providers, the work doesn’t stop when the curve gets back to the bottom. First they have to prepare for a possible resurgence and restock supplies. Canada’s pandemic plan also calls for various provincial health systems to put together immunization programs, if a vaccine exists, and evaluate the psychological effect of the outbreak on the public.

EFFectiveness OF PHYSICAL distancing

during pandemics

The authors of a study, published in Emerging

Infectious Diseases, conducted a systematic

review of the effectiveness of six physical-dis-

tancing measures during past flu pandemics.

They concluded that early implementation

delayed the peak in the number of infections,

relieving the burden on health-care systems by

spreading out the cases over a longer period

of time.

Without measures

With measures

Number of infections

Delaying the

peak of infections

reduces the burden

on health-care systems

Capacity of

health-care system

Cases are spread out

over longer period

Time since first case identified

JOHN SOPINSKI/THE GLOBE AND MAIL, SOURCE:

fondazione gimbe (via m.w. fong et al, cdc,

emerging infectious diseases)

EFFectiveness OF PHYSICAL distancing

during pandemics

The authors of a study, published in Emerging Infectious

Diseases, conducted a systematic review of the effective

ness of six physical-distancing measures during past flu

pandemics. They concluded that early implementation

delayed the peak in the number of infections, relieving

the burden on health-care systems by spreading out the

cases over a longer period of time.

Without measures

With measures

Delaying the

peak of infections

reduces the burden

on health-care systems

Number of infections

Capacity of health-care system

Cases are spread out

over longer time period

Time since first case identified

JOHN SOPINSKI/THE GLOBE AND MAIL, SOURCE: fondazione

gimbe (via m.w. fong et al, cdc, emerging

infectious diseases)

EFFectiveness OF PHYSICAL distancing during pandemics

The authors of a study, published in Emerging Infectious Diseases, conducted

a systematic review of the effectiveness of six physical-distancing measures during past flu pan-

demics. They concluded that early implementation delayed the peak in the number of infec-

tions, relieving the burden on health-care systems by spreading out the cases over a longer

period of time.

Without measures

With measures

Delaying the

peak of infections

reduces the burden

on health-care systems

Number of infections

Capacity of healthcare system

Cases are spread out

over longer time period

Time since first case identified

JOHN SOPINSKI/THE GLOBE AND MAIL, SOURCE: fondazione gimbe

(via m.w. fong et al, cdc, emerging infectious diseases)

Compiled by Globe staff

With reports from The Canadian Press and Carly Weeks

Sign up for the Coronavirus Update newsletter to read the day’s essential coronavirus news, features and explainers written by Globe reporters.