The victims of the deadliest flu pandemic in history were killed when their bodies unleashed an uncontrolled immune reaction as a protective mechanism, say scientists. Patients’ lungs rapidly became inflamed and filled with blood and other fluids which eventually drowned them. The discovery could help emergency authorities prepare for flu pandemics caused by the H5N1 avian flu virus, which appears to kill in a similar way. It may also give scientists ideas for making flu vaccines. In 1918 a strain of influenza ravaged populations around the world, killing an estimated 50 million people before it eventually died out. In a bid to understand why this strain, called the Spanish flu, was so dangerous, American scientists re-constructed the virus in 2005. In the latest experiment scientists used the re-constructed virus to infect macaque monkeys. They found that the over-reaction of the immune system destroyed the monkeys’ lungs within a week. There are strong parallels between this reaction and the one that almost killed six volunteers who were given the experimental antibody drug TGN1412 at London’s Northwick Park hospital in March last year. Both the virus and the drug caused a surge of cytokines, the molecules in the […]