If the analogy succeeds, it suggests that mandatory vaccination policies are permissible—which is to say coercion can be used to promote vaccination—because non-vaccinators are not entitled to harm or risk harming non-liable bystanders, just as shooters are not entitled to harm or risk harming their neighbors.
Opponents of mandatory vaccination policies may resist this analogy at several points. One may argue that contagious transmission is a natural occurrence or part of God’s plan, whereas bullets falling from the sky is a result of human behavior, and that people are therefore entitled to demand a gunfire-free community but not to make demands on nature or God. Or, vaccination opponents may argue that the risk of being harmed by an unvaccinated person, especially in light of herd immunity, is very small. Critics of vaccination requirements may also argue that any individual’s contribution to the harm or risk of harm that is posed by non-vaccination is negligible, so individuals do nothing wrong by refusing vaccination. In the rest of this section, I will show that these attempts to resist the analogy fail, and that non-vaccination is indeed harmful in the same way that random gunfire is harmful.
First, consider the claim that non-vaccination is morally different from celebratory gunfire because we are not entitled to a disease-free community when disease is a natural occurrence or part of God’s plan. Or, perhaps those who oppose vaccines could make the argument that gunfire and transmitting a disease are different because we do not have rights against being harmed by natural events like diseases, earthquakes, or epidemics. It may be true for diseases that do not result from human negligence or maleficence that they are a part of nature, just like falling rocks. However, when a disease can be prevented by immunization, the transmission of the disease cannot be solely attributed to nature but is also attributable to someone’s failure to prevent transmission, just as falling bullets are attributable both to human action and gravity.
That diseases can be used as weapons illustrates the following point. When British soldiers distributed smallpox infected blankets to the Shawnee and Delaware tribes during the siege of Fort Pitt and at other times in the eighteenth century, they violated the rights of the tribes’ members even though smallpox was a naturally occurring disease (Fenn 2000). Even non-maleficent cases of disease transmission can be wrong. If a person negligently infects an uninformed partner with a sexually transmitted disease, or if a company exposes unknowing workers to carcinogenic chemicals, they have also violated people’s entitlements to a disease-free environment, even if people do not have general rights against STD’s or cancer (Harris and Holm 1995).
Another intuitive difference between gunfire and disease is that gunfire makes people worse off, whereas vaccination may seem like a choice to not make people better off. Here the objection is that vaccination is a benefit and non-vaccination is therefore a failure to benefit. Since there is a moral asymmetry between refraining from harm and failing to benefit where the latter is less morally serious, non-vaccination is much less morally serious than gunfire.
The distinction between harming and failing to benefit is difficult to sustain without providing independent arguments about people’s entitlements (Quinn 1989). As I argued earlier in this essay, people have entitlements against being made sick by others, so I am skeptical that the premise of this objection is sound. However, even if we were to accept the implicit theory of harm in this defense of non-vaccination, the defense still does not succeed because it assumes that the normative baseline by which we assess non-vaccinators is the baseline of zero vaccination. This is a mistake because we needn’t assume that an event is harmful only if it makes us worse than we would be in our natural state.Footnote 6 After all, we do not assess other cases of harm against the standard of a lawless state of nature, so why should we understand the harm of non-vaccination in this way? Instead, we should assume that deviations from a policy mass immunization are harmful just as we assume that deviations from a policy that prohibits celebratory gunfire is harmful even if there would be far more celebratory gunfire in the absence of laws against it.
But, perhaps the claim that non-vaccination isn’t harmful relies instead on a non-comparative account of harm where harm is not defined in terms of a baseline but in terms of simply being in a bad state, like a state of pain. Such a defense might succeed if it only means that non-vaccination itself is not harmful on this account of harm, but non-vaccination does cause harm because it causes people to get sick and being sick is a bad state to be in.Footnote 7
Non-vaccinators may also resist the gunfire analogy on the grounds that the risk of being harmed by an unvaccinated person, especially in light of herd immunity, is very small, unlike the risk of being hit by a stray bullet. We can imagine, however, that the risk of being hit by a stray bullet is also very small but that random gunfire is wrong and rightly prohibited nevertheless. One reason that public policy can limit random gunfire or non-vaccination is that even small risks become morally significant when they are taken many times and the overall potential for harm outweighs the low probability of harm actually happening in any single case. Small risks are also morally significant when the potential harm affects a lot of people.Footnote 8 Non-vaccination can take this form. Even if a single non-vaccinator’s choice does not impose significant risks on many people, as an increasing minority makes a risky choice the pool of people who are exposed to the risks of transmission becomes greater, so the risk of non-vaccination becomes more significant. Furthermore, even a single non-vaccinator imposes small risks on people who have high stakes. If an unvaccinated person transmits a contagious illness to someone who is immunosuppressed, such as a cancer patient or an infant, the consequences can be deadly.
These features of non-vaccination show that even if the risks associated with a single individual’s refusal of vaccines are small it is a mistake to ignore the harm of a single unvaccinated person simply because the risk of harm is small (Parfit 1984). Individuals can be responsible for the harmful things they do together, even if any particular individual’s contribution is seemingly minor. This principle gains force as more people make a risky and harmful choice like remaining unvaccinated, especially because the risks can affect many people and the stakes are exceedingly high for the victims of the risky behavior.
A related asymmetry between celebratory gunfire and non-vaccination is that a single unvaccinated person’s contribution to reducing the harm or risk of harm posed by the entire unvaccinated population is especially small, given high rates of vaccine refusal. We can modify the celebratory gunfire case to better reflect this seeming asymmetry simply by increasing the number of neighbors who fire weapons. Adding more people to the group that poses a threat to innocents may make any one individual’s contribution to the threat less substantial, but that shooter nonetheless poses a threat in that his bullet could be the one that lodges in your shoulder.
If anything, the harm of non-vaccination is even worse than the harm of celebratory gunfire, because part of the harm, in addition to the harm of transmission itself, is the harm of decreased herd immunity. Unlike celebratory gunfire, non-vaccinators not only are more likely to transmit an illness, they make it more likely that others will transmit harmful diseases as well. Non-vaccinators may reply that their specific contribution to herd immunity is insignificant, that it is so negligible that one individual’s failure to vaccinate does not actually make anyone worse off. Yet, just because the effect on herd immunity is small or imperceptible does not mean that it is not harmful. Actions that have very small effects, like overfishing or imposing small traffic delays on others, can be extremely harmful in aggregate (Parfit 1984). And, just as every fisherman in fact has an effect on overfishing by taking fish out of the water, each non-vaccinator has an effect on undermining herd immunity by taking himself out of the pool of inoculated citizens.
The idea that people have rights to not be subjected to serious risks without their consent requires that we define a baseline level of acceptable risk. Not all small risks merit moral consideration. We impose small risks on people every day. Every driver risks killing an innocent person but I am not suggesting that driving should be prohibited. Part of what should determine whether an activity imposes undue risks on others is the costs of avoiding those risks and one’s reasons for imposing the risks. For some vaccines, the risk of non-vaccination may be so small (e.g., if the disease has been eradicated) that compulsory immunization is not warranted. But the earlier examples of recent outbreaks show that, at least in some cases (pertussis, measles), the risks of refusal are significant and that innocent people die because of non-vaccination. In the next sections, I will show that the reasons for avoiding the risks of transmission and threat to herd immunity associated with vaccine refusal cannot be justified on the basis of most reasons that are given.
It may also be permissible to small impose risks on others if one’s contribution to a bad outcome would not be of any consequence because the outcome is over-determined. In the case of vaccination, however, it is a mistake to characterize non-vaccinators as “free-riders” who benefit from an over-determined outcome because each individual non-vaccinator weakens herd immunity, even if the effect is imperceptible.Footnote 9 The risks posed by vaccine refusal are also more morally significant than other small risks that we collectively impose on others, like the risks associated with pollution because a single refusal is theoretically sufficient for transmitting an illness and harming or killing an innocent.Footnote 10