Of pandemics and epidemics

The World Health Organization has just used the word ‘pandemic’ to describe the spread of the coronavirus across the globe, prompting a spike in searches for the word on the Collins Dictionary website. The dictionary definition of a pandemic is ‘an occurrence of a disease that affects many people over a very wide area’, and it is the phrase ‘a very wide area’ that differentiates a pandemic from an epidemic, which is also a serious outbreak of disease, but is confined to a particular region.

Breaking down the difference between these two words requires a little excursion into ancient Greek. Both words share the ending ‘-demic’, which comes from the Greek word ‘demos’. ‘Demos’ means ‘the people’, and is also the root of the English words ‘demography’ (the scientific study of population) and ‘demographic’. But what makes the difference between an epidemic and a pandemic in terms of word-formation is the Greek-derived prefix at the start of each word. The prefix ‘epi-’ means ‘at’ or ‘over’ (as in words such as ‘epicentre’), whereas ‘pan-’ means ‘all’ (as in ‘pan-American’). So a pandemic affects not just one population, but pretty much all the populations in the world.

From the perspective of the WHO, pandemics are much rarer than epidemics, and the word has been reserved for major events such the outbreak of Spanish flu in 1918 and the spread of HIV/AIDS in the 1980s. Both of those pandemics resulted in millions of deaths around the world. Let us hope that the consequences of the coronavirus will be less severe.