The so-called Mexican flu virus - though it has nothing to do with Mexico - occurs in most people as a mild form of the common seasonal variant. However, it is a danger to several risk groups, including pregnant women, especially in the second and third trimesters. The majority of the fatalities in Britain this year were pregnant women. So far in Belgium, one person has tested positive, though the case was not serious enough to require hospitalisation.

The standard flu vaccine contains H1N1, so there is no need for a special or additional jab for those who have already had one. Van Ranst's office has also requested that GPs report all cases of respiratory infection so that further tests can be done to rule out the presence of the H1N1 virus. The virus is more contagious than seasonal flu, and infected people are contagious for longer. Advice to help stop spreading the virus is the same as for seasonal flu: cover the mouth when coughing and sneezing, wash hands regularly and use paper tissues. And, if you are infected, don't go to work: your boss may thank you, but your colleagues won't.