The day that we have just looked at and another one a few days later are much higher than any other points. They do not follow the general pattern of the graph of a gradual increase in number of cases reported and then a more rapid decrease in the number of cases reported.

These anomalous points are very interesting for the WHO and they look for explanations.

Here are some hypotheses as to why the number of reported cases was so different on those days;

These problems with reporting of cases affected the ability of the WHO epidemiologists to study the incidence and distribution of information. It meant that the WHO was making public health decisions based on incomplete data.

As a result of this the international health regulations of 2005 ensured that the accurate sharing of information was required by member states.