Tuesday, September 20, 2005

Official Death Predictions Grossly Conservative

Predicting exactly how many deaths a pandemic could cause is tricky. There are a lot of variables to take into account, and guessing which ones would come into play, and how much impact they would have is beyond my ability. However rough estimates can be made based on readily available information. These estimates are not exact, and could be off by a lot. However expecting them to be off as far as the official estimates is an unrealistic streach.

Most of the numbers I have seen quoted look like rehashes of the so-called Spanish Flu of 1918, or are even more conservative than that. This seems preposterous considering that the world population today is almost 4 times what it was in 1918. So even if all we were dealing with was a re-enactment of 1918 we should be expecting quadruple the number of deaths. Then there is the little fact that the spanish flu killed less than 10% of those it infected while H5N1 kills at least 50%. Taking this into account as well a basline figure should be about 20 times the spanish flu's death toll world wide. Since the Spanish flu left 20-50 million dead in 1918, we could expect H5N1 to take 400 million to 1 billion lives, but recent data suggests that the mortality rate for H5N1 infections has increased, so my numbers could be conservative. All of this is assuming little or no vaccination or effective use of antiviral drugs on a global scale. Some will certainly be used by the wealthier nations, but many nations have no capability to produce vaccines, and the most effective antiviral drugs are in short supply. Even if antiviarals are used, they seem to be of only limited effectvieness, and the virus is likely to become resistant fairly quickly, as was seen with the Chinese use of antivirals to control the disease in their chicken populations.

In 1918, America saw between 500,000 and 675,000 people lose their lives to the Spanish flu. America's population is about 2.5 times what it was in 1918. Multiplied by 5 for the increase in mortality exhibited by H5N1 versus the Spanish flu, and we should expect 12.5 times what our loses were that time around, or between 6.3 million and 8.4 million deaths if a vaccine could not be produced before the end of the flu season. Another way of evaluating this number is that 10-20% of Americans contract the flu in a given season, between 27.5 million and 55 million people. Assuming that 1/3 contract the H5N1 strain, and half of those die would suggest between 4.6 and 9.2 million deaths. Agian if H5N1's mortality rates have indeed increased as some experts are claiming then these numbers could be very much on the conservative side.

Death tolls this high in America are extremely unlikely however. About the only chance of them occuring would be if H5N1 managed to break out into the global human population as a full-fledged pandemic virus between now and the start of the flu season. This is quite unlikely based on current trends. If it doesn't break out until spring, then even if the standard schedule for produceing a vaccine were followed with no notable accelleration most of those lives would be saved, since the greatest majority of cases would occur during the flu season. I estimate that each month leading up to the beginning of the flu season would see 0.2% of the total deaths that could be expected from the disease. When the flu season hit, this number would jump dramatically. The aim of the standard schedule for producing the vaccine is to have the vaccine ready before the flu season starts, thus preventing the worst effects of the jump in cases that could be expected at that time.

The problem with H5N1 is that (assuming the worst case without vaccination would be about 7 million people dead in the United States) we could expect about 14,000 Americans would die for each month before the vaccine was ready, compared with up to 2 million a month once the flu season hit. Depending on how long it took to get vaccine production up to speed we are talking 50,000-100,000 dead. If it were impossible to avoid those deaths that would be one thing. If a new strain emerged and we had production capacity ready but needed to wait until a vaccine could be created, that would be understandable. If the only reason those people had to die was because we didn't prepare ahead of time only because we lacked the will to do so, that would be unforgivable. For our lawmakers to be willing to waste billions on pork projects but be unable to justify the spending needed to prepare for this epidemic would be beyond contempt.

Each of us has a nearly equal chance of falling victim, though admittedly those of us in coastal cities have the greatest risk, both because the flu is more likely to reach us before a vaccine is ready, and because the density and mobility of a large urban population gives the virus an ideal area within which to spread. If the harm to our fellow citizens, and the cost to our nation in medical bills and lost work was not enough we should also consider that some of those killed will undoubtedly be friends, relatives, perhaps close family, or even ourselves.

1 Comments:

At 9:58 AM, Blogger Lisa said...

For the past month, H1N1 mutations have been popping up all over the world. Organizations such as yourself, who have been the catalyst for the spread of awareness and extensive research, are important now, more than ever. We at, Disease.com (a site dedicated to to disease treatments and preventions), are inspired by the great work by your organization, and would like to join you in the fight. If you could, please list us as a resource or host our social book mark button, it would be much appreciated. It is about time we get rid of this "national emergency".If you want more information on that please email me back with the subject line as your URL

 

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