Greg’s flu – ‘Merville Fever’ as he called it yesterday – continued. Today he said it was Spanish Flu. Unsurprisingly, he did not fly.
Diary
Friday June 21st. Stayed in bed all day. (Known in England as ‘Spanish Flu’.)
Spanish Flu
Greg equates what was evidently known within 42 Squadron as ‘Merville Fever’ with Spanish Flu. Possibly the words in brackets in his diary entry were added at a later date. But in any event, can he really have been talking about the same ‘Spanish Influenza’ that killed so many in 1918 and 1919? Especially if, as he said yesterday, it was merely “a sort of ‘flu lasting three or four days”?
Perhaps surprisingly, the answer was quite probably ‘yes’ – for a couple of reasons. (Nice bit of epidemiology coming up.)
The W-Curve
First, he was the right age not to be too badly affected. At 19 and in good health he would have had a fairly robust constitution. Furthermore, the 1918-19 influenza pandemic did not affect all age groups equally. Mortality was greatest among children under four and among the elderly – two immunocompromised groups – as one might expect. Also, there was also a curious minor peak of mortality among those aged 25-34, but Greg’s age put him only on the lower slopes of that peak.
Because of the minor peak among 25-34 year olds, a plot of mortality rate against age for the 1918-19 pandemic became known as the W-curve. This contrasts with the more expected U-curve that was seen in earlier years between pandemics:
The Three Waves
Secondly, as shown by the following plot of mortality rate against time (not age of patient, as in the above figure) there were three waves of the 1918-19 influenza pandemic, of unequal lethality. They were:
- A first, mild wave in June/July 1918;
- The second, most severe wave in Autumn 1918; and
- A third, moderately severe wave in Spring 1919.
We see this three-wave pattern even more clearly from the UK data shown in Figure 1 of Taubenberger & Morens (2006), cited above:
Greg’s illness was in the first wave, which had the least rate of mortality of the three waves.
Not a Great Threat
So all in all, Spanish Flu – or Merville Fever – was by this stage not the great threat that it became, particularly for a young man of his age. At the time, it was quite plausibly regarded as “a sort of ‘flu lasting three or four days”. This is entirely in line with the observation by Taubenberger & Morens (2006) that:
Despite the extraordinary number of global deaths, most influenza cases in 1918 (>95% in most locales in industrialized nations) were mild and essentially indistinguishable from influenza cases today.