In connection with the Mexican flu you always heard the word pandemic, but what does that actually mean?
A pandemic is an infectious disease that spreads quickly and easily among people across large geographical areas. While an epidemic can be limited to one country, a pandemic - in the worst case - affects people all over the world.
For both pandemics and epidemics, the number of infected people is rising much faster than expected for a certain period. In principle it does not matter how many people are affected by the disease.
The annual flu that breaks out all over the world during the cold winter season is not yet an epidemic or pandemic, because it is always expected and in many cases can even be predicted very precisely.
In the same way, the extremely common virus type 1 herpes, which has infected 90% of the population, cannot be called a pandemic or epidemic because the percentage of infected people does not increase appreciably but remains virtually the same. Furthermore, no specific requirements are set for the severity of the disease, so in principle a completely innocent infection can also be a pandemic.
The World Health Organization WHO officially determines when a disease is a pandemic. The Mexican flu, or influenza A (H1N1), was referred to as a pandemic in 2009. But other types of flu also developed into a pandemic at the time: in 1918-1919 the Spanish flu, which killed one in three world citizens and killed as many as 40 million people, and in 1968-1969 the Hong Kong flu.