The Coronavirus Pandemic: Understanding the Terminology
The world’s media has focused its attention on one single issue: the coronavirus pandemic. Information on television and the radio regarding this pandemic is continuous, and we all wake up every morning concerned about the development of the disease in our country.
The daily cumulative number of deaths and infections is an essential statistic in understanding the development of a disease. Even so, we need to understand other parameters to interpret these figures correctly. For this reason, we’d like to take the opportunity to try to clearly explain certain different epidemiological terms that are key to putting the current situation into perspective.
Defining the coronavirus pandemic
In the last few days and weeks, we’ve had to familiarize ourselves with terms such as outbreak, epidemic, and pandemic. The last term has attracted the most attention of all since it’s the one that experts are using to talk about the global problem caused by COVID-19. But let’s take a look at what these terms really mean.
An epidemiological outbreak refers to the sudden appearance of an infectious disease in a specific place at a specific time. For example, food poisoning located in specific geographical areas that are eventually identified and resolved is an example of an outbreak.
When an outbreak gets out of control and actively spreads, it leads to an epidemic. The coronavirus (COVID-19) was classified as an epidemic during the first months of its expansion. Its spread was uncontrolled, but only within China and in the case of limited identified outbreaks in other countries.
On March 12, the coronavirus crisis was identified as a pandemic by the World Health Organization (WHO). To do so, the disease had to meet two requirements: first, that it was affecting more than one continent, and also that there were non-imported community cases.
When a person becomes infected without having been in contact with an imported case, then it’s time to suspect that the disease is circulating freely in the country. This is when the authorities can announce a state of pandemic.
Fatality and mortality: A numbers game
Now that we’ve determined these basic terms, let’s put the official figures for those affected into perspective. There’s a phrase that may be familiar to us, but which isn’t entirely correct. This phrase is: “the coronavirus mortality rate is …“.
Let’s see why.
Overall mortality rate
The overall mortality rate is the proportion of people who die in relation to the total population over a period of time. As Spain is one of the countries most affected by the pandemic, let’s take it as an example.
The mortality rate in Spain in 2018 was 9.1%. That is to say, out of every 1,000 inhabitants, 9.1 died in that year. There isn’t any differentiation by cause; this data simply represents the proportion of deaths in a geographical area.
The fatality rate of the coronavirus pandemic
The correct term when talking about the number of deaths from coronavirus is the fatality rate.
This refers to the proportion of people who die from a specific disease. Experts calculate this based on a percentage of those affected by it in a given period and area. The calculation is the number of deaths divided by the number of those recovered plus the deaths.
This rate has us all on edge. It seems that, depending on the country, it can vary enormously. In China, it was 3%, whereas in Spain it has reached almost 9%. These are undoubtedly figures that can give great cause for concern.
So, why do some countries seem to be “unluckier” in this pandemic?
The fatality rate is a difficult parameter to interpret
- In China, up to one-third of those infected were identified as being asymptomatic. In many other countries, such as Spain, a person must display certain symptoms to be tested. If you’re sick enough to have to go to the hospital, then the disease has already had an impact on you. The fact of the matter is that if the country were to take into account the number of patients with mild symptoms – those who have had the disease but haven’t gone to hospital – then there would be a lower fatality rate.
- The fatality rate is also highly dependent on the average age in the country. We know that the coronavirus affects the elderly more aggressively, and so the older the population, the higher the rate. That doesn’t mean that the virus is more lethal in one place than another, but simply that there’s a higher percentage of vulnerable people. The right thing to do is to identify the fatalities by age group, thus eliminating this bias.
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Incidence of the coronavirus pandemic
Cumulative incidence is defined as the proportion of healthy individuals who develop the disease over a given period.
We’ll continue to take Spain as an example here. At this time, the incidence in Spain is 96.56. In other words, almost 97 people per 100,000 inhabitants have been infected. Again, these values would be higher if the statisticians took all the cases of mild symptoms not recorded into account.
Nevertheless, the incidence is a very important parameter in understanding a pandemic. Unfortunately, the numbers are frightening: we’re talking about thousands of infected people. However, we mustn’t lose sight of the fact of the total population of each country, which can be tens or hundreds of millions.
Knowledge and peace of mind
These values in no way mean we shouldn’t take that the restrictions imposed on us seriously. We’re facing a situation of exceptional gravity; that’s why, without everyone’s co-operation, numbers could soar even higher in the coming weeks.
What we’ve tried to emphasize in this article is the need for perspective. In this coronavirus pandemic, the numbers are high and certainly worrying. However, we need to have a theoretical understanding of what’s happening so that we don’t succumb to hypochondria, misunderstandings, fear, and panic.