A century ago half of all human deaths were due to infectious diseases. Today the proportion has come down to one quarter, mainly thanks to vaccines, antibiotics and improved living conditions. There is however a class of pathogens that has evaded human arms. These pathogens change their structure and so become insensitive both to drugs that used to work and immunity developed thanks to vaccines or disease. One of these pathogens which we have not managed to definitively block is the influenza virus. About 10% of the human population gets influenza every year, many millions go to hospital with complications of the disease and about half a million people die. The influenza virus has an almost unlimited ability to evolve and in its always new form it succeeds in evading our defenses. Now, thanks to the work of a Cambridge University research group things could be about to change. With help from the Institute of Informatics and Statistics a system has been developed that should be able to foresee the virus’s next move. Instead of responding to its moves we anticipate them. The task seemed impossible as the possible new forms from one year to the next are about one thousand billion. However, after 15 years of study, of the possible mutations only about 40 are likely and this number comes down further when preparing the vaccine because many of the mutations are meaningless.