The pandemic wiped out up to 100 million lives, but scientists still struggle to explain what caused it. The answers could ensure that it never strikes again
One hundred years ago this month, just as the first world war was drawing to a fitful close, an influenza virus unlike any before or since swept across the British Isles, felling soldiers and civilians alike. One of the first casualties was the British prime minister and war leader, David Lloyd George.
On 11 September 1918, Lloyd George, riding high on news of recent Allied successes, arrived in Manchester to be presented with the keys to the city. Female munitions workers and soldiers home on furlough cheered his passage from Piccadilly train station to Albert Square. But later that evening, he developed a sore throat and fever and collapsed.
He spent the next 10 days confined to a sickbed in Manchester town hall, too ill to move and with a respirator to aid his breathing. Newspapers, including the Manchester Guardian, underplayed the severity of his condition for fear of presenting the Germans with a propaganda coup. But, according to his valet, it had been touch and go.
Lloyd George, then aged 55, survived, but others were not so lucky. In an era before antibiotics and vaccines, the Spanish influenza so-called because neutral Spain was one of the few countries in 1918 where correspondents were free to report on the outbreak claimed the lives of nearly 250,000 Britons. Cruelly for a nation that had seen the flower of British male youth mown down by German guns, the majority were adults aged 20 to 40. The mortality was the inverse of most flu seasons, when deaths fall most heavily on the elderly and the under-fives.
The global death toll was inconceivable: according to the most recent estimates, between 50 million and 100 million people worldwide perished in the three pandemic waves between the spring of 1918 and the winter of 1919. Adjusting for population growth, that is equivalent to between 200 million and 425 million today.
Unlike now, when reports of new bird flu outbreaks in south-east Asia are closely monitored by the World Health Organisation, there was no early warning system. Consequently, when it was reported in May 1918 that King Alfonso XIII was ill in Madrid, most people dismissed the Spanish flu as a joke. The main advice was to gargle with salt water and to isolate yourself until the fever had passed. However, these rules did not apply to munitions workers who were urged to carry on for the sake of the war effort.
As in other 20th-century epidemics and pandemics, such as HIV/Aids, Africans and Asians suffered proportionately more than Europeans and north Americans. Thus, while the average case mortality in the developed world was about 2%, in India, where 18.5 million perished, it was 6%, and in Egypt, where 138,000 died, it was 10%. In isolated regions with virgin populations with no immunity to flu, the impact was truly astonishing in Western Samoa, for example, a quarter of the population was wiped out. By contrast, American Samoa recorded no casualties.
The severity of the pandemic and the peculiar death pattern puzzle scientists to this day. Few epidemiologists believe the pandemic began in Spain, pointing instead to pre-pandemic waves in Copenhagen and other northern European cities in the summer of 1918. Where the virus first leapt from birds to humans or some other mammal is even more perplexing, with some scientists favouring a Kansas point of origin and others northern France or China.
Earlier this year, in search of answers for a new podcast series, I travelled to Washington DC to interview one of the worlds leading experts on the 1918 pandemic. Jeffrey Taubenberger, a molecular pathologist at the National Institute of Allergy and Infectious Diseases, has been studying the Spanish flu virus for more than 30 years. In the late 1990s he succeeded in retrieving fragments of viral RNA from stored pathology specimens taken from American soldiers who had died of flu at US army camps in 1918 and an Inuit woman who been buried on a beach in Alaska, where the permafrost had preserved her lung tissue from decay.
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