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May 08, 2007

tetanus

To start on vaccines (remember, I am not giving specific medical advice, but discussing general principles): Let’s take the one that elicits the most frequent fear response, tetanus. Tetanus is a horrible disease, causing a horrible death. The lockjaw, then generalized tetany, has been known from antiquity. The organism was isolated in 1889. The concept of protection by transferred antitoxin was demonstrated in 1897. The toxoid, a formaldehyde-treated toxin, was developed in 1924, and by WWII was in wide use. By the late 1940’s, tetanus was introduced into routine childhood immunization.

Remember that there was a significant steady decrease in deaths from tetanus from the mid-1800’s, when records were first kept. Even the CDC's Pink book states, “A marked decrease in mortality from tetanus occurred from the early 1900’s to the late 1940’s.” At that time, the late 40’s, there were about 0.4 cases/100,000 (or 500) per year. About 30% of the cases were dying. Now less than 10% of people with tetanus die, and we are down to about 20 per year, or less than 0.01/100,000 (1/15 million).

Perhaps the vaccine can be credited with decreasing both the mortality and incidence of tetanus. The rate of decline doesn’t support that, but it is still possible. Even if the vaccine is responsible for that decrease, it is still only a few hundred people out of 300 million. Remember our lightning death rate is exactly the same. Dying of tetanus, even without the shot, is a 1/million chance, the quintessential act of God. Yet to prevent that, we go crazy, spending precious time, energy, and care to race around to get a tetanus shot. Puncture wounds account for half of tetanus cases, so maybe stepping on a nail is a good reason to make the effort for a shot. But self-piercing and tatooing account for a fair number also. So avoid those.

Not sure | By Robert Maddox | 11:12 PM

Comments

On my ER rotation I was told that a tetanus shot after stepping on a rusty nail (for instance) won't do you much good, because by the time your immune system gets around to benefiting from the booster, you would be already affected by any pathogens on the nail. The real reason (according to the ER attending) is that persons who do one risky thing (step on a nail) are liable to do it again, or something else dangerous. Any thoughts on that?

Posted by: Alice at May 12, 2007 03:45 PM

Alice, You should ask one of the immunology experts that while you still have a chance. But I think the window of 72 hours was set allowing time for the booster to work before the toxin was formed by the bug. The ER skepticism is typical though (I write as an ER doc for 20 years). To reiterate my main point, your chance of dying of tetanus is about your chance of dying of a lightning strike.

Posted by: Robert Maddox at May 14, 2007 11:36 AM

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