The Asian flu pandemic of 1957 killed up to 4 million people, including about 40,000 in the UK. It was the second big flu pandemic of the century but, unlike the catastrophic 1918 outbreak, it did not catch the world entirely unprepared.

In 1918, around a quarter to a third of the world's population fell ill and 50 million may have died. But the H2N2 strain of flu that emerged in 1957 was milder than the one responsible for such devastation and modern virology, vaccines and antibiotics to treat complications had arrived.

The first news of extensive outbreaks came from Hong Kong and Singapore at the start of May. Later it became clear these had spread from a province in China at the end of February. By mid-May, laboratories had identified the virus as a new subtype which had evolved from chickens or ducks and mingled with human strains to produce a virus that could spread rapidly from one person to another. Less than six months after its arrival in Hong Kong, every country in the world had experienced cases.

In Europe and the US, the epidemic exploded as children returned to school in September. In the first wave, it was mainly children who went down with flu because of their close contact with friends. It then spread from children to the elderly - where most of the fatalities occurred.

But vaccine manufacturers were rapidly on the case and by August in the US and October in the UK, there was a vaccine available, although not nearly enough to go round because of insufficient manufacturing capacity. In some countries public gatherings were banned and schools were closed, but these only delayed the spread. By December, the worst was over as many developed immunity by suffering a mild bout of flu, and by 1968 the virus had disappeared - except in laboratories.