(Macmillan, £15.99)
The question of forgetting lies at the heart of Mark Honigsbaum's Living with Enza. Both my parents were teenagers in 1918-19. Neither of them ever mentioned the great global pandemic of influenza, which killed 228,000 Britons and at least 50m people during those years, on every inhabited continent. Why did they, and so many of their contemporaries, put it out of mind? Perhaps the war-weary world could face no more mass death; perhaps bad things which take place over a relatively long period (in this case about eight months) fade rapidly from memory. Yet this was death on a scale unmatched even by the recent war; and the 50m figure is almost certainly an underestimate. There were many other deaths to follow the main pandemic: from depression, suicide, and complications of the central nervous system, notably Economo's disease, the "sleeping sickness" endemic to Europe and North America from 1919 to 1929 so graphically described by Oliver Sacks in his book Awakenings.
Minor influenza epidemics are not uncommon—they simply entail an unusually high incidence of a strain of influenza in a given population, as can occur in most countries at some point during most winters. An influenza pandemic, however, represents an outbreak of disease across a far larger region, such as a continent, associated with much higher rates of illness and death than any ordinary seasonal epidemic. Three conditions are necessary for a pandemic: a novel virus, its ability to cause illness, and the ability of the virus to be transmitted between humans. The H5N1 flu virus, "avian influenza," has been a potential pandemic threat since 2003. At present, only the final condition is in doubt with regard to H5N1, because person to person transmission seems to have taken place in very few cases and under unusual circumstances. A new influenza pandemic will certainly occur in the future, although not necessarily as a result of H5N1.
One of Honigsbaum's most illuminating descriptions is of how, in 1918-19, there was tension between Arthur Newsholme, chief medical officer of the Local Government Board, and James Niven, the medical officer of health for Manchester. The former encouraged people to go about their business as usual while the latter advised quarantine and social distancing. Niven's quarantine strategy proved effective. In Manchester, where his measures were widely practised, infections and death rates were lower than elsewhere in Britain. This remained so until the armistice celebrations on 11th November 1918, which brought crowds to the streets, throwing people into close proximity. A week later, the Manchester Evening News proclaimed: "Alarming Increase in Manchester Mortality."
Today, the tension between these two messages remains at the heart of Britain's potential response to pandemic influenza. The British government's goal is to maintain "business as usual." However, some simulation models suggest that the advantage of early school closure—a key element of social distancing—is very high in terms of potential lives saved. And the margin for making this decision is a matter of days—these viruses cut through populations very rapidly. In the face of this type of evidence, governments face very difficult decisions. Currently, pandemic influenza is assessed as the greatest single risk confronting Britain. Although less likely to occur than some other threats—for example terrorist attacks on crowded places—its potential impact is enormous.
Influenza is a slippery virus because, like HIV, it is a retrovirus; a group of viruses with exceptionally high rates of mutation and the ability to combine with other viruses or with variants of themselves. Although we may not have an influenza pandemic this winter, next year or the year after, most informed observers believe the probability of a pandemic some time soon is very high. Mark Honigsbaum's book shows just how devastating such an event could be. Furthermore, he highlights the dilemmas faced by politicians and policy advisers who may have to choose between recommending "social prophylaxis" (preventing us from breathing and sneezing on each other and the surfaces we may touch in the course of a day) or urging people to "carry on as usual."
We commemorate the losses of the first world war with the phrase "lest we forget." Unless we apply the same lesson to the pandemic that followed it, however, the cost of forgetfulness may prove just as high as the cost of war.
