The big question for all of us this week is: How serious a threat is swine flu? All the evidence suggests that we are prepared as never before for a flu pandemic. We have enough anti-viral drugs to treat half the population because we have seen this coming for a number of years. We were expecting bird flu, but have swine flu instead.

Those who suffered in the 1918 pandemic did not enjoy the warnings we have had. Nor could they possibly have enjoyed the medical advances we have since taken.

We cannot predict the course that swine flu will take. Despite the deaths in Mexico, the evidence outside that country thus far suggests that it has only caused relatively mild symptoms.

Most experts, however, will not be drawn on the eventual danger posed by this virus on the grounds that they do not know.

We are nonetheless reassured by what we have heard so far.