Sunday, July 3, 2016

Public vs. Private Health

As we close in on the Summer Olympics in Rio de Jeneiro, the persistence of the Zika virus problem has led to various recommendations, not all of them official. Some say attendance poses a hazard to certain people, like pregnant women, so those people should not attend. Others worry about the possibility of male to female sexual transmission (which is a thing) and so, what? Maybe no one should attend? All of this angst overlays concerns about the displacement of native Brazilians from their homes during the construction of Olympic venues, the shifting of public money into that construction, money that many Brazilians have said could have been used for education, health care, and improving the lives of the poor--all things that would materially improve the public health. Meanwhile, pharmaceutical companies, funded in part by public dollars, are trying to develop a vaccine. More public money is going toward mosquito abatement, although there are those who warn that some approaches (like genetically engineered mosquitoes, GEM) could have untoward environmental consequences, themselves a threat to public health.

I once asked my teacher at homeopathic medical school if he could discuss the "health issues of vaccines." He responded with, "Vaccines aren't a health issue, they're a public health issue." He went on to say that we are taught to view vaccination as an individual medical intervention. But the "benefits" of immunization programs are not necessarily individually oriented; they are oriented toward a manipulation of the environment in which germs must live, to make that environment inhospitable for those germs. They're an environmental intervention.

Take smallpox for example. It has only one possible host: man. If all humans are successfully immunized, the environment for smallpox disappears. It has no place to reside. This is exactly what has occurred with smallpox, and now the only known examples of this virus exist in laboratories in Russia and the U.S. The disease is gone.

Smallpox did kill a lot of people (ask the Indians of North America), so this killing off of wild smallpox seems like a real win. It's possible that the existence of smallpox had some sort of environmental upside, but to date I haven't seen anything like that reported. This shouldn't be dismissed casually. In working toward management of the Zika problem, some proposals have us killing most mosquitoes using either poisonous sprays or genetically engineered mosquito-attacking germs or even GEMs themselves, which would reduce or eliminate the bug's ability to breed.

Terrific! No mosquitoes!--except that mosquitoes are food for many birds and beneficial insects. We've seen successful mosquito-borne disease reductions in many parts of the world. Yellow fever, malaria, and other diseases have been reduced, mostly at this moment by using poisons. But then those poisons have ended up in the food chain and come with their own public health risks.

And the use of these approaches assumes that the majority of people in affected areas support the benefits of these programs and accept the risks.

What I have observed in practice is that the selection of acceptable risks by individuals is a lot more complex. The individual calculus of risk acceptance isn't the same as the calculus used by public agents (citizens, policy-makers, doctors and nurses) to decide what measures should be imposed on everyone in a jurisdiction or an environment.

In upcoming posts I'll tackle the vaccine issue with this in mind. To get us started, I circle back to my teacher's comment about the real issues in immunization: public versus private health. The former is a collective decision that makes a choice about what is valuable for all and what the acceptable risks are for society as a whole. The latter is an individual decision undertaken in private with one's clinician. Such benefits and risks are based on particular features of the person. Here's an example: A person accepts his nurse practitioner's offer of a tetanus booster shot because she knows the man has a high risk of suffering dirty wounds in the course of his work as farmer. Opposite this would be the person who declines the offer, because she has a history of tetanus allergy, even though she has suffered a dirty wound.

If that sounds far-fetched, it's not. I had a patient once who nearly died because the doctor insisted she try a tetanus shot for an injury she suffered from an electric fan blade. We resuscitated her, but it was a close call!

One might ask, What's the risk of getting tetanus from such a wound? In about a half hour of searching the scientific literature on this Sunday morning, I have been unable to find an "attack rate" for tetanus. That is, I couldn't find information that would predict the number of people who get the disease tetanus ("lock jaw") from any wound, or from specific types of wounds ("clean", "dirty", etc.). This makes some sense, because conventional wisdom says that the risk of a known adverse reaction from the tetanus vaccine is fairly low, and the risk of dying from tetanus is about 13%. Furthermore, almost all cases of tetanus occur in unvaccinated people, or in people who'd been vaccinated but then didn't get boosters for long periods. Their protection had waned.

The numbers are small enough that attack rates for certain kinds of wounds haven't been calculated. Tetanus itself is a disease that is caused by a specific event: a wound, usually dirty and deep (hence the rusty-nail-in-the-foot as a common cause, in the popular mind). Tetanus from other types of wounds (paper cuts, shallow wounds, scrapes, blunt trauma, cuts from kitchen knives, etc.) is rare.

But tetanus isn't a disease that spreads from person to person, like measles, whooping cough, or diptheria, among others. When that's the case, how does it reframe our discussion? The vaccine "debate" has two poles: those who believe it to be necessary and those who believe it is not. Each side demonizes the other. Advocates argue that immunization is a medical marvel that saves lives with little adverse consequence. Opponents argue that it's unecological, harmful, and even a plot by Big Pharma to make money.

In upcoming posts, I'll deconstruct this argument in a different way.

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