Wednesday, February 10, 2010

Viral irrationalism

Jerusalem Post opinion "Viral irrationalism" (February 8th, 2010) reports on the failure of Jews to inoculate their children against basic diseases. It recommends required immunization, while Corrections remains uncertain as to whether or not such a requirement would be welfare-enhancing.

The Jewish community, here and in the Diaspora, is not immune to such irrationalism. Some people have been instructed by their clerics not to immunize; some have been swept up in the quagmire of medical quackery, while still others are convinced profiteering pharmaceutical companies are conspiring to promote unnecessary vaccines.

After establishing that Hasidic Jews have experienced outbreaks of mumps, the article urges required inoculation.

We urge the Health Ministry to consider requiring parents to provide a child’s pinkas hisunim – immunization record – when they register their youngsters for school. The enforcement tool would be simple: Any municipality or stream, including most of the haredi sector, which is found to admit unimmunized children, would face loss of funding from the national government.

The only reason Corrections can see that a government might get involved in required inoculation is that it represents a positive externality through herd immunity. Herd immunity is a concept in epidemiology that allows for the protection of non-inoculated individuals because enough of the herd is immune. In brief, the concept is as follows: if one person has the disease, and they give it to (on average) less than one other individual, then there will be no outbreaks. The herd is largely "immune." If they give it to (on average) more than one other individual, then there will be exponential growth in a disease and outbreaks will ensue.

So long as a society is past herd immunity thresholds, they have decreasing returns to further inoculation, in terms of herd immunity. In such a case, required inoculation can easily be seen as welfare-decreasing, especially as all other individuals have the option of becoming inoculated.

The threshold for herd immunity in mumps is approximately 80%. Israel passed that threshold in 1990. Corrections notes that among humanity's most valuable accomplishments has been the eradication of smallpox through vaccination. Vaccination has great value. However, given that the critical herd immunity threshold has been passed, allowing Jewish parents to make their own decisions about the risks of their children dying is much cheaper.

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