# 3532
As I’ve stated from the very beginning of this pandemic outbreak, I don’t have a very good `feel’ for the severity of this virus. The reports we get are obviously incomplete and inexact, making any accurate calculations of the mortality rate almost impossible to make.
My unscientific sense – based on the reports I’ve seen - is that the absolute mortality rate of this virus (so far) may be equivalent to, or perhaps even lower than, seasonal flu.
Which would be good news, and cause for celebration, except that those who are dying from this virus are almost all under the age of 65.
Normally, influenza (and pneumonia) takes its greatest toll among the elderly. But this virus (like other pandemics of the past) appears to have a predilection for younger victims, and in particular, pregnant women.
And anytime an illness claims younger lives, it tends to amplify its impact on society. We expect death to come to the elderly and the infirmed – not to the young and healthy.
Today, the editor of the British Medical Journal weighs in on the problems of calculating the CFR (Case Fatality Ratio) of this pandemic.
Predicting and preparing for pandemic flu
Fiona Godlee, editor, BMJ
"Never make predictions," said the American baseball player Casey Stengel, "especially about the future." But we have to forecast if we are to plan. For more accurate forecasting in this flu pandemic, it’s essential for us to refine our methods and to understand their limitations. This is what Tini Garske and colleagues seek to do in their fast tracked article in this week’s journal (doi:10.1136/bmj.b2840).
The world needs to know how many people are likely to die from the new flu virus. Data emerging from different countries offer widely different pictures. The initial reports from Mexico suggested high fatality ratios among those infected, sparking a sense of panic. Mexico’s fatality ratios are still among the highest in the world, but Gaske et al explain that the cause is unlikely to be an especially virulent version of the virus—instead, under-reporting of mild cases could explain the trend. If we take these cases into account, the true case fatality ratios could be much lower and more in line with those for seasonal flu. But because there’s no herd immunity to this new virus, many more people will catch it and the absolute numbers of cases and deaths will almost certainly be much greater than for seasonal flu, they say.
It seems that I’m not alone in not having a good handle on the CFR of this virus. Others are waiting for `good data and rigorous methodology’, as well.
While we tend to focus on the death rate of a pandemic, that isn’t the only serious impact that a pandemic outbreak can deliver.
- A high attack rate – even with a low mortality rate – could still produce a much higher death toll than we normally see with influenza.
- A high morbidity-low mortality illness would place enormous stresses on our healthcare delivery system, and could cause collateral deaths among non-flu patients as a result.
- High absenteeism due to illness could seriously affect the delivery of essential good and services.
- And high absenteeism could seriously affect the economy.
So while a low CFR pandemic would be a bit of a blessing, it certainly doesn’t mean that we will come away unscathed. And, of course, there are no guarantees that this virus won’t gain virulence along the way.
Some things to think about as we continue to work the numbers.
