In all of the planning that's been going on in my public health work, the big worry is that this will repeat the pattern of the 1918 pandemic:
- The disease shows up in a weak form in the spring, makes some people mildly ill, kills some people who are traditionally susceptible to influenza (very young, elderly, and people with chronic disease)
- The disease mostly disappears through the summer--not entirely, but becomes much less common
- The disease shows up again in the fall in a new, much more virulent form, and has a much higher mortality rate, especially among healthy adults. See this graph
, which shows how the mortality among different ages was very different from traditional influenza.
There is no guarantee that this would happen, and no guarantee that it won't peter out like the 1976 fiasco. But we see it as a better bet to risk the accusation of an overreaction than to risk not being prepared.