The precautionary principle: plan for the worst, hope for the best

When the WHO Director-General declared the pandemic, it met all the criteria of a pandemic. In the early stages of the event, it was impossible to know whether the pandemic would resemble the severe pandemic of 1918-19, or a much more mild pandemic. Initial indications coming out of Mexico were of a very severe event.

While WHO elaborated various scenarios, including severe events, and spoke of these in its documents and on its web site, the world was fortunate in that the pandemic turned out to be moderate in its effects. This was made clear by the WHO Director-General in her statements during the course of the event.

The exact death toll of the pandemic will never be known. Laboratory-confirmed deaths were 18 500, but this number under-states the true number of deaths. Moreover, severe disease and deaths did occur, with up to one third to half occurring in previously healthy young and middle-aged people. This coupled with the fact that influenza viruses are unpredictable, supports the caution opted for by decision-makers and public health officials. The world used the precautionary principle to protect lives, which has to be part of any security plan.