Yesterday, I discussed the need to define the assumptions which will guide your pandemic preparations. We also noted that planning will involve some "known" factors plus some variables which are "unknown but forecastable" and some which are "unknown and unknowable."
A logical starting place for your planning assumptions is the U.S. government's top-level list of pandemic planning assumptions. I present those below.
(By the way, if you've already been making pandemic preparations for your household or business, but never actually listed your planning assumptions, it's not too late. Listing these "knowns" and "unknowns" might help you fine-tune your preparations.)
The U.S. Pandemic Influenza Plan issued by the Department of Health and Human Services observes that, "Pandemic preparedness planning is based on assumptions regarding the evolution and impacts of a pandemic."
The Plan cites the past experiences used in developing the planning assumptions. (Such experience-based assumptions involve "Unknown-Forecastable" variables.):
The 20th century pandemics have ... shared similar characteristics. In each pandemic, about 30% of the U.S. population developed illness, with about half seeking medical care. Children have tended to have the highest rates of illness, though not of severe disease and death. Geographical spread in each pandemic was rapid and virtually all communities experienced outbreaks.Pandemic planning is based on the following assumptions about pandemic disease:
- Susceptibility to the pandemic influenza subtype will be universal. [Everyone will be susceptible to catching this flu. Since a pandemic is caused by an influenza virus that's new to humans, no one has natural immunity. The subtype of great concern now is influenza A (H5N1). -Chirp]
- The clinical disease attack rate will be 30% in the overall population. Illness rates will be highest among school-aged children (about 40%) and decline with age. Among working adults, an average of 20% will become ill during a community outbreak.
- Of those who become ill with influenza, 50% will seek outpatient medical care.
- The number of hospitalizations and deaths will depend on the virulence of the pandemic virus. Estimates differ about 10-fold between more and less severe scenarios. Because the virulence of the influenza virus that causes the next pandemic cannot be predicted, two scenarios are presented based on extrapolation of past pandemic experience (Table 1).
For hospitalizations and deaths, the referenced table shows:
Moderate Pandemic (1958/68-like):
Hospitalizations - 865,000
Deaths - 209,000
Severe Pandemic (1918-like):
Hospitalizations - 9,900,000
Deaths - 1,903,000
Also, translating the "clinical disease" percentages into numbers:
Sickness (30% of population) = 90 million people
Outpatient care (50% of sick) = 45 million people
On average, about one million people in each state would be sick enough to go to the doctor.
How does that assumption impact you, your business, school, hospital, etc.?
