The picture we have of the 1918 flu pandemic is vastly more detailed today than it was 20 years ago, let alone 50 or 100 years ago. But it’s nowhere near complete. Pathologist Jeffery Taubenberger of the US National Institute of Allergy and Infectious Diseases – the man who in 2005, with his colleague Ann Reid, published the genetic sequence of the virus responsible for the pandemic – said at a recent conference there were still many unanswered outstanding questions.
Researchers all over the world are working hard to answer them. But what they have already uncovered might surprise you.
The fittest were among the most vulnerable
Austrian artist Egon Schiele died of influenza in October 1918, just a few days after his wife Edith, who was pregnant with their first child. In the interim, though desperately sick and grieving, he worked on a painting that depicted a family – his own – that would never exist.
Schiele was 28 years old, firmly within an age group that proved acutely vulnerable to the 1918 flu. It is one reason why his unfinished painting, The Family, is often described as a poignant testimony to the disease's cruelty.
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Because it was so deadly to 20-to-40-year-olds, the disease robbed families of their breadwinners and communities of their pillars, leaving large numbers of elderly people and orphans with no means of support. Men were at greater risk of dying than women, in general, unless the women were pregnant – in which case they died or suffered miscarriages in droves.
Scientists don't know precisely why those in the prime of life were so vulnerable, but a possible clue lies in the fact that the elderly – always a high-risk group for flu – were actually less likely to die in the 1918 pandemic than they had been in flu seasons throughout the previous decade.
One theory that potentially explains both observations is "original antigenic sin" – the idea that a person's immune system mounts its most effective response to the first strain of flu it encounters. Flu is a highly labile virus, meaning that it changes its structure all the time – including that of the two main antigens on its surface, known by the shorthand H and N, that engage with the host's immune system.