The Numbers Game
# 688
When it comes to pandemic planning, it is obvious that not all governments, and their agencies, are on the same page.
Yesterday we learned that the UK was now looking at an attack rate during a pandemic of 50% instead of the commonly assumed 30% used in most planning models. They are still apparently using a 2.5% fatality rate, at least based on their estimates of 750,000 deaths in the UK.
Today, Waterloo, Ontario released their pandemic plan, and the numbers they are using for a severe pandemic pale in comparison.
Protocol sets out treatment priorities and plans for convalescent centres
ANNE KELLY AND FRANCES BARRICK
WATERLOO REGION (Apr 21, 2007)
Six to 10 local high schools will become flu clinics where ill people will be assessed and treated during a pandemic flu outbreak, according to a regional pandemic plan released yesterday.
The 293-page report, which was nearly two years in the making, outlines how the region will respond to an influenza pandemic. It is based on a worst-case scenario, in which a particularly virulent strain could sicken 35 per cent of the population in waves over a period of 12 to 18 months.
If the infection rate is that high, it is estimated 743 people will die. Nearly 2,500 will be hospitalized and there will be nearly 130,000 outpatient visits.
The sickest patients would be admitted to hospitals and the least ill sent home. In the next phase of planning, the region will looking for potential sites for two or three convalescent centres, possibly in university or college residences, vacant institutions or hotels. They would be recovery areas for patients who are too sick to go home but not sick enough to be hospitalized.
Dr. Liana Nolan, the region's medical officer of health, said she has the power, if necessary, to cancel large gatherings, such as parades and hockey games, to control the spread of the virus. Schools may also be shut down.
But Nolan said she would not quarantine people, since it's nearly impossible to prevent the spread of the flu.
The plan is an impressive 294 pages, filled with charts, graphs, and pandemic battle plans. But their assumption that, out of a population of 485,000 people, they would see a maximum of 743 deaths, would seem overly optimistic when compared to other pandemic plans.
Their assumption, stated in section 2.5 of their plan is:
"It is important to note that approximately 95% of those who become infected will not need traditional medical care."
That's a mighty big assumption.
The rough numbers in their plan are based on 485,000 residents, and a maximum attack rate of 35%. That would mean 170,000 people infected, although they only expect 129,000 to seek outpatient care.
Out of those, they expect no more than 2,489 to require hospital services, or a little more than 1.4%.
And out of those 170,000 infections, they only expect 437 deaths, but admit it could run as high as 743 deaths.
In other words, they expect a fatality rate of less than 1/2 percent.
If we were to apply the Florida assumptions to this plan, they would need to be planning for 17,000 hospitalizations and 3,400 deaths.
And if you applied the UK's 50% attack rate, and a 2.5% fatality rate assumption, they'd be looking at over 6,000 deaths.
Of course, no one knows what the next pandemic will bring. Right now, based on the 60% mortality rate of H5N1 victims, even a 2.5% fatality rate looks low.
It is disconcerting that we have such wide divergence in what communities, and nations, are planning for. The Waterloo plan obviously envisions a `severe' pandemic as having far less of an impact on their community than the 1918 pandemic.
While I certainly hope, if a pandemic comes, it will be a mild one; it hardly makes sense to bet the farm on that.
