Vaccines have saved more lives and prevented more suffering than any medical invention ever conceived by humans. However, to be most effective, a large enough fraction of the population to produce herd immunity needs to be immunized. When the herd immunity threshold is reached, then the chances of anyone carrying a microorganism to cause disease drops, leaving no reservoir of infectious agent to facilitate disease spread. The end result is that the unvaccinated are also protected, which is important for children who can’t be vaccinated because they are either too young, have a medical contraindication to vaccination, or are among the fraction of people for whom the vaccine doesn’t produce lasting immunity. Herd immunity also, ironically enough, protects vaccine refuseniks, too.
The exact fraction necessary for herd immunity varies depending upon the vaccine and the disease, but it’s usually somewhere around 90%. As long as the percentage of vaccinated children stays above herd immunity, there’s no serious problem; outbreaks can’t propagate. But, as vaccination rates fall, outbreaks become possible. In any case, the question of vaccine refuseniks raises an interesting ethical problem, namely how vaccine refuseniks obtain most of the advantages of vaccination without taking upon themselves any of the even tiny risk of being vaccinated.
Janet Stemwedel has written a lucid and nuanced piece about the bioethical questions involved in vaccine refusal and concludes that, yes, vaccine refuseniks are free riders.
I understand that the decision not to vaccinate is often driven by concerns about what costs those who receive the vaccines might bear, and whether those costs might be worse than the benefits secured by vaccination. Set aside for the moment the issue of whether these concerns are well grounded in fact. Instead, let’s look at the parallel me might draw:
If I vaccinate my kids, no matter what your views about the etiology of autism and asthma, you are not going to claim that my kids getting their shots raise your kids’ odds of getting autism or asthma. But if you don’t vaccinate your kids, even if I vaccinate mine, your decision does raise my kids’ chance of catching preventable infectious diseases. My decision to vaccinate doesn’t hurt you (and probably helps you in the ways discussed above). Your decision not to vaccinate could well hurt me.
The asymmetry of these choices is pretty unavoidable.
But if a significant number of people disagree, and think the potential harms of vaccination outweigh the potential harms of the diseases, shouldn’t they be able to opt out of this social contract?
The only way to do this without being a free-rider is to opt out of the herd altogether — or to ensure that your actions do not bring additional costs to the folks who are abiding by the social contract. If you’re planning on getting those diseases naturally, this would mean taking responsibility for keeping the germs contained and away from the herd (which, after all, contains members who are vulnerable owing to age, medical reasons they could not be vaccinated, or the chance of less than complete immunity from the vaccines). No work, no school, no supermarkets, no playgrounds, no municipal swimming pools, no doctor’s office waiting rooms, nothing while you might be able to transmit the germs. The whole time you’re able to transmit the germs, you need to isolate yourself from the members of society whose default assumption is vaccination. Otherwise, you endanger members of the herd who bore the costs of achieving herd immunity while reaping benefits (of generally disease-free work, school, supermarkets, playgrounds, municipal swimming pools, doctor’s office waiting rooms, and so forth, for which you opted out of paying your fair share).
Which is what I’ve been saying all along: Sure, go ahead and don’t vaccinate. But don’t expect to go to public schools, day care centers, or any place else with high concentrations of people among which infectious disease can be spread. Isolate yourself geographically, if necessary. Anything less, and you are a freeloader. (Janet is too nice.)