As you may have seen, on Wednesday evening, the new coronavirus outbreak has been officially characterised as a pandemic by the World Health Organisation. The Director General said that “we are deeply concerned both by the alarming levels of spread and severity, and by the alarming levels of inaction” and so this latest outbreak has become “the first pandemic caused by a coronavirus”.

All the terminology around this crisis can sometimes be confusing. What is a pandemic? Why have the WHO declared a pandemic now? Have we had pandemics before and how does this change things? I’m going to try to answer some of these questions below and hopefully help to clarify any confusion you may have. As has been said in all the videos about COVID-19, please bear in mind that any information or statistics that I use from the current outbreak were correct at the time of recording and make sure you check the latest advice from your local authority or government for the latest advice in your country. As I’ve said before, stay alert but not anxious.

What is a pandemic? What’s the difference between an epidemic and a pandemic?

Words such as epidemic or pandemic are quite often thrown around in everyday life to refer to aspects of life that aren’t always health related. In health terms though a pandemic relates to the geographic spread of a disease rather than any changes in the nature of the disease itself. According to the WHO, a pandemic is "an epidemic occurring worldwide, or over a very wide area, crossing international boundaries and usually affecting a large number of people." Other health bodies such as the CDC in America defines a pandemic as "an epidemic that has spread over several countries or continents, usually affecting a large number of people”. There isn’t a specific threshold in terms of infections, deaths or countries affected and so the distinctions between outbreaks, epidemics, pandemics etc are often blurred but essentially, a pandemic is global in nature and is considered to be more serious than an epidemic which is geographically more constrained. You may also hear words or phrases like outbreak or cluster. Outbreak carries the same definition of epidemic, but is often used for a more limited geographic area. Cluster refers to an aggregation of cases grouped in place and time that are suspected to be greater than the number expected, even though the expected number may not be known.

How does the WHO decide when to confirm an infection as a pandemic? Why have they decided to make this decision now?

So, obviously the WHO have been keeping track of this disease very closely for the past couple of months and on 30th January they declared that the situation had become a global health emergency. As I said earlier, there isn’t a specific threshold in terms of infections, deaths or countries affected but based on the available evidence, the WHO decided that this was necessary at that point in order to raise the level of concern around the virus.

In terms of when the WHO decide to ‘declare’ an infection as a pandemic – that’s quite a complicated question. In fact, WHO no longer ‘declare’ any infections as ‘pandemics’ but instead ‘characterise’ them as pandemics instead – it’s a subtle change but one which is important. Previously, they used a six phase system of levels to decide on when to declare a pandemic. As you can see these ranged from phase 1 when ‘no animal influenza virus circulating among animals have been reported to cause infection in humans’ to phase 6 when a pandemic is declared when there is “human-to-human spread in at least one country outside of the two in the initial WHO region”.

The pandemic phases were developed in 1999 and provided a global framework to aid countries in pandemic preparedness and response planning. However, last month a spokesman for WHO told Reuters news agency that “WHO does not use the old system of 6 phases that ranged from phase 1 (no reports of animal influenza causing human infections) to phase 6 (a pandemic) that some people may be familiar with from H1N1 in 2009”.

In fact, some people think that it was because of what happened in 2009 that the system was changed. During that outbreak, the WHO declared swine flu or H1N1 “a pandemic” based on the six-phase system, which caused unnecessary panic and led to some criticism after pharmaceutical companies and governments spent money on developing antiviral medications for a disease which turned out to be comparatively mild.

As this paper looking at pandemics states:

“In 2009, governments throughout the world mounted large and costly responses to the H1N1 influenza outbreak. These efforts were largely justified on the premise that H1N1 influenza and seasonal influenza required different management, a premise reinforced by the decision on the part of the World Health Organization (WHO) to label the H1N1 influenza outbreak a "pandemic". However, the outbreak had far less serious consequences than experts had predicted, a fact that led many to wonder if the public health responses to H1N1 had not been disproportionately aggressive”

The fact that the WHO were criticised quite widely after the swine flu outbreak perhaps indicates why they have been wary about characterising COVID-19 as a pandemic before now.

Have there been pandemics like this in the past?

Clearly one of the most infamous from history is the Plague in the 14th century which resulted in the deaths of an estimated 75 to 200 million people in Eurasia. In total, the plague may have reduced the world population from an estimated 475 million to 350–375 million. In more recent history, the Spanish influenza after the First World War claimed the lives of up to 50 million people worldwide in one year and, on a more long-term scale, smallpox became a pandemic in the 20th century claiming the lives of between 300 to 500 million people. In 1959, the World Health Organization (WHO) launched a campaign to globally eradicate smallpox and in 1980, smallpox was declared eradicated.

How worried should we be? How does this change things?

Essentially, this doesn’t change anything in terms of the action that you need to take immediately. The WHO have stressed that declaring a pandemic does not mark a change in its own advice and it’s still urging people to “detect, test, treat, isolate, trace and mobilise their people” to try to contain the virus. It’s important that changing the word doesn’t suddenly cause unnecessary panic – the disease has not changed and your own personal risk hasn’t suddenly increased. So there is no need to panic.

But we should still take the decision by the WHO seriously. It’s clear that they are now extremely concerned by the spread of the virus to multiple countries and declaring a pandemic may well push some governments into declaring more stringent measures such as the ones which will be discussed in an upcoming video.


For now, the advice should still be – stay calm, alert and aware of the measures being put in place in your country but don’t panic. The positive news from the past week has been that new cases being recorded in Wuhan province in China, where this outbreak began, are now down to single figures on a daily basis. We should all take confidence from this as we move forward over the next few weeks.

#alertnotanxious