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Archive for December 19th, 2008

Influenza Deaths

“There are known knowns. These are things we know that we know. There are known unknowns. That is to say, there are things that we know we don’t know. But there are also unknown unknowns. There are things we don’t know we don’t know.”- Donald Rumsfeld

How do we know what we know? It is said by some anti-vaccine proponents that vaccines are not needed because the diseases they prevent are either gone or no longer as severe as they were in pre vaccine times. People may have suffered and died in the distant past, but no longer. The risk now is from the vaccines not the diseases they no longer prevent.

36,000 people, more or less, die every year from influenza. That is the number of deaths according to the CDC web site; the NEJM review uses the higher number of 56,000 (7). Which number is correct? Isn’t that why the flu vaccine is recommended: to prevent all those people from dying.

36,000 is a lot of people. That’s about 120 deaths per million people in the US. In Oregon, population about 3 million, that would be about 360 people a year, which is two deaths a day for the six month flu season.

“Death is caused by swallowing small amounts of saliva over a long period of time.”–George Carlin.

2,400,000 people die every year in the US, about 6600 a day. In Oregon, that is about 65 deaths a day. No one outside a epidemiologist is going to notice 2 extra deaths a day during flu season. I have seen a lot of people die of influenza, but I have a biased experience: I am an infectious disease doc, so I am likely to see people with influenza, especially patients with disease severe enough to kill them.

About the same number of people die from car accidents and die from handguns in the US each year as die from influenza. I have never known a person in my real, as opposed to my professional, life to die from influenza or handguns or a car accident. My personal experience suggests no one dies from these causes, but since I take care of patients at one of the Portland trauma hospitals, I know what cars and guns do to people. My professional life confirms that people do indeed die from being shot or car accidents. I would wager that most people reading this blog have not known anyone who has died from influenza, guns or car accidents. The fact that people do die of influenza seems contradicted by experience. Why get the vaccine? I don’t get the flu and and no one I know has ever died from it.

As an illustrative example, a relative of mine, a retired physician, mentioned that he thought the shingles vaccine was a waste of time and money as he had never known anyone to get shingles. Using personal experience to judge disease prevalence is unreliable. If I applied the same rationale to driving, I would not wear a seat belt as I have never been in a high speed crash.

36,000 people die of influenza each year. What is the source of that statistic? From “Mortality associated with influenza and respiratory syncytial virus in the United States”. JAMA 2003. Is that really how many deaths are there from influenza? It depends on what you mean by ‘death’ and what you mean by ‘influenza’ and what you mean by ‘from’.

“It depends on what the meaning of the words ‘is’ is.” – Bill Clinton

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Posted in: Basic Science, General, Public Health, Vaccines

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