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Vaccine Refusal Is Not Free Riding

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Abstract

Vaccine refusal is not a free rider problem. The claim that vaccine refusers are free riders is inconsistent with the beliefs and motivations of most vaccine refusers. This claim also inaccurately depicts the relationship between an individual’s immunization choice, their ability to enjoy the benefits of community protection, and the costs and benefits that individuals experience from immunization and community protection. Modeling vaccine refusers as free riders also likely distorts the ethical analysis of vaccine refusal and may lead to unsuccessful policy interventions.
Erasmus Journal for Philosophy and Economics,
Volume 14, Issue 1,
Spring 2021, pp. 167181.
https://doi.org/10.23941/ejpe.v14i1.555
Vaccine Refusal Is Not Free Riding
ETHAN BRADLEY
Oakland University
MARK NAVIN
Oakland University
Abstract: Vaccine refusal is not a free rider problem. The claim that vac-
cine refusers are free riders is inconsistent with the beliefs and motiva-
tions of most vaccine refusers. This claim also inaccurately depicts the
relationship between an individual’s immunization choice, their ability to
enjoy the benefits of community protection, and the costs and benefits
that individuals experience from immunization and community protec-
tion. Modeling vaccine refusers as free riders also likely distorts the ethi-
cal analysis of vaccine refusal and may lead to unsuccessful policy inter-
ventions.
Keywords: fairness, free riding, game theory, public health, vaccination
JEL Classification: C72, I18
I. INTRODUCTION
The Covid-19 pandemic has highlighted problems of non-compliance with
public health guidelines. Some people refuse to wear masks in public, to
engage in social distancing, or even to avoid large gatherings (Breslow
2020; Glanz et al. 2020; van Rooij et al. 2020). Of particular interest to us
is that some have indicated an unwillingness to receive Covid-19 vaccines
(Freeman et al., forthcoming; Lazarus et al. 2021). Refusal of Covid-19
vaccines would therefore seem to be another instance of the general phe-
nomenon of vaccine refusal, which has recently contributed to outbreaks
of previously well-controlled infections (Jacobson, St. Sauver, and Finney
Rutten 2015; Phadke et al. 2016).
Researchers have sometimes characterized vaccine refusal as a free
rider problem (Bauch, Bhattacharyya, and Ball 2010; Betsch, Böhm, and
Korn 2013; Betsch et al. 2017; Buttenheim and Asch 2013; van den Hoven
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2012; May and Silverman 2005; Schröder-Bäck et al. 2009; Siegal, Siegal,
and Bonnie 2009). That is, they have claimed that vaccine refusers pro-
mote their individual interest by benefitting from the community’s pro-
tection from infection without also making a contribution to the commu-
nity’s protection by becoming vaccinated themselves.
1
Notably, this char-
acterization of vaccine refusers applies only in cases in which the com-
munity already has protection against infectionthat is, when a suffi-
ciently large percentage of the population, having been vaccinated, is im-
mune to the disease so that outbreaks are unlikely. Most countries pos-
sess community protection for many vaccine-preventable diseases, in-
cluding, for example, polio (Global Polio Eradication Initiative n.d.).
Though none yet have community protection against Covid-19, we may
hope that ongoing vaccine distribution efforts will soon generate it.
The diagnosis of vaccine refusal as a kind of free riding is supposed
to inform our understanding of the origins of vaccine refusal (vaccine re-
fusers rationally pursue their own interests), the ethical analysis of vaccine
refusal (vaccine refusers make unfair use of community protection), and
potential policy responses (vaccine refusers will vaccinate if one makes
slight changes to their incentives).
But, as we shall argue, vaccine refusal is not a kind of free riding. First,
a free rider model misrepresents the subjective motivations of most vac-
cine refusers. Vaccine refusers often doubt that vaccines provide benefits
to individuals and communities, and often radically overstate the risks
associated with vaccination. That is, vaccine refusers do not think they
are using a valuable public good (community protection) or that they are
refusing to make a reasonable contribution to that good since they think
the expected costs of vaccination are very high. Second, a free rider model
misstates the objective relationship between individual vaccination
choices and one’s ability to benefit from community protection. A free
rider benefits from a public good that they could also be contributing to,
but it is not possible to both contribute to community protection and to
benefit from it. This is because the means by which a person contributes
to community protection (individual immunity, usually generated
through vaccination) makes it impossible for that same person to benefit
1
We follow contemporary usage in referring to ‘community protection’, rather than ‘herd
immunity’, because the community is protected rather than immune and because we are
speaking of a moral community of human persons rather than a passive animal herd
(Anderson et al. 2018).
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from community protection.
2
Furthermore, the act of ‘contributing’ to
community protection (by becoming vaccinated) is, by itself, individually
rational, even when community immunization rates are high, because
there is rarely an objective anticipated cost of vaccination for individuals.
Free riding is individually rational, by definition, but refusing vaccines
rarely is.
II. VACCINE REFUSAL AS FREE RIDING
An individual is a free rider if they enjoy the benefits of a public good
(that is, a good that is non-rivalrous and non-excludable) without also
contributing to it, even though they could also contribute to the good,
and even though the personal benefits they acquire from the public good
would outweigh their personal costs of contribution (Olson 1965). Free
riding creates a collective action problem: it is individually rational to free
ride, but if enough people free ride, then no one can, since insufficient
contribution undermines or destroys the good that they were attempting
to enjoy. That is a collectively irrational outcome. In this way, free riding
problems may take the shape of a Prisoner’s Dilemma, wherein a social
good can be created by cooperation, but each individual benefits from
defecting (Hardin 1971).
Furthermore, some have argued that free riding is ethically wrong
when the public good is sufficiently valuable and the costs of contribution
are sufficiently low. On this kind of view, free riding is not only collec-
tively irrational, but also individually unethical, because it is unfair to
benefit from the contributions of others without making a reasonable
contribution oneself (Cullity 1995).
If vaccine refusal were a kind of free riding, then (1) mass vaccination
must create a public good, (2) it must be possible for individuals to con-
tribute to that good and also to benefit from it, though (3) it must be
better for individuals not to contribute, but just to benefit from it. Fur-
thermore, vaccine refusers would have an intention to free ride just in
case they intended to enjoy the benefits of the public good that mass
vaccination creates, but they did not intend to pay the (small) costs asso-
ciated with contributing to that good.
2
An individual can (1) intend to contribute to community protection (by getting vac-
cinated) without actually contributing to community protection (if the vaccine does not
give them immunity), and (2) continue to benefit from community protection. But such
a person does not both contribute to and benefit from community protection.
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Mass vaccination creates a public good. ‘Community protection’
(sometimes called ‘herd immunity’) exists when a community has a suffi-
ciently high rate of individual immunity, such that outbreaks are highly
unlikely and such that it is highly improbable that individuals who are
not immune to infection will become infected (Anderson et al. 2018). The
logic of free riding on community protection may seem straightforward:
vaccination has expected costs for individuals, including time, money,
and risks of side effects and adverse events. Community protection has
many expected benefits for individuals, including decreased morbidity
and mortality. The benefits an individual enjoys from community protec-
tion outweigh the individual costs associated with vaccination. However,
someone who free rides on community protection enjoys the benefits of
community protection without paying any costs associated with contrib-
uting to it.
Scholars writing about empirical issues in vaccine refusal have some-
times modeled vaccine refusal as a form of free riding (Bauch,
Bhattacharyya, and Ball 2010; Betsch, Böhm, and Korn 2013; Betsch et al.
2017; Buttenheim and Asch 2013; van den Hoven 2012; Ibuka et al. 2014;
May and Silverman 2005; Siegal, Siegal, and Bonnie 2009). The details of
their models differ. For example, Bauch and colleagues (2010) show that
free riding practices can develop quickly after the introduction of a vac-
cine that is universally and freely available but not mandatory. For an-
other example, Ibuka and colleagues (2014) found that individuals were
less likely to vaccinate in a simulation when the rate of vaccination was
high in the previous round of the simulation. But the common thread that
ties together ‘free riding’ models of vaccine refusal is that vaccine refus-
ers pursue their rational self-interest in avoiding the costs associated with
vaccination while benefiting from the vaccination behaviors of others.
People who have written about the ethical issues involved in vaccine
refusal have also sometimes invoked the idea that refusers are free riders
who make selfish and unfair use of others’ contributions to community
protection (Clarke, Giubilini, and Walker 2017; Dawson 2007; Giubilini,
Douglas, and Savulescu 2017; Giubilini 2019; Hendrix et al. 2016; van den
Hoven 2012; Navin 2016; Salmon and Siegel 2001). Some have argued that
one goal of immunization policy is to fairly distribute the burden of
achieving community protection while avoiding unfair free riding. For ex-
ample, they have proposed that nonmedical exemptions to vaccine man-
dates only be granted to people who make an alternative contribution to
public healththat is, contributions similar to those of some conscripted
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pacifists who are asked to provide alternative (for example, non-combat-
ant) services to a war effort (Clarke, Giubilini, and Walker 2017; Giubilini,
Douglas, and Savulescu 2017).
III. WHY NOT FREE RIDING?
Vaccine refusal is not a case of free riding. Vaccine refusers do not have
the subjective beliefs and attitudes of free riders, and the objective costs
and benefits associated with vaccine refusal are not consistent with free
riding.
III.I. Beliefs and Attitudes
Vaccine refusers rarely possess the beliefs and attitudes towards vaccina-
tion and community protection that are consistent with them being sub-
jective free riders. Someone intends to free ride when they recognize the
benefits of a public good that they are enjoying and when they
acknowledge that they are benefitting from that good without making a
reasonable contribution to it. For example, in Prisoner’s Dilemma models,
a defector (who wishes to be a free rider) seeks to take advantage of the
benefits of other people’s cooperative behavior without themselves en-
gaging in cooperative behavior. Vaccine refusers do not fit this profile.
First, vaccine refusers often believe that vaccines are ineffective, that vac-
cines do not cultivate individual immunity to disease, and that commu-
nity protection does not exist (Harmsen et al. 2013; Sobo 2016). Others
are wholly unfamiliar with the concept of community protection (Quadri-
Sheriff et al. 2012; Sobo 2016). Such vaccine refusers cannot be motivated
by a desire to take advantage of others’ cooperative behavior because they
do not think other people’s vaccination choices create a public good.
There are some exceptions. For example, Dr. Bob Sears recommends that
parents who refuse vaccines for their children do not “share their fears
with their neighbors, because if too many people avoid the MMR [measles,
mumps, and rubella vaccine], we’ll likely see the disease increase signifi-
cantly” (Sears 2007, 96–97). The clear implication is that parents of chil-
dren in Sears’ practice should want other parents to continue to vaccinate
so that their own children will be safe from disease. But it is rare to see
vaccine refusers acknowledge that they are benefitting from other peo-
ple’s decisions to vaccinate. A more common view is that vaccines are
ineffective, that they are collectively harmful, and that everyone would be
better off if no one were vaccinated (Dubé et al. 2013; Harmsen et al. 2013;
Sobo 2016).
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Second, part of the idea of free riding is that it better promotes an
individual’s interests than contribution does, but that contributing to
(and enjoying) a public good is better for the individual than non-contri-
bution and non-enjoyment of the public good would be. This is because
an individual’s costs of contribution are outweighed by the benefits they
receive from the public good. So, even though free riding on a public good
is individually rational, contribution is also beneficial (though less so than
free riding) compared to not enjoying the public good at all. In the case
of modeling vaccine refusal as free riding, a free rider would better pro-
mote their own interests than would someone who were vaccinated, but
a vaccinated person enjoying community protection would better pro-
mote their own interests than would someone who did not benefit from
community protection at all. On such a view, an individual’s expected
costs of vaccination are more than compensated for by the benefits they
receive from community protection.
But many vaccine refusers do not believe that the expected costs of
vaccination are low. They reject the scientific consensus that vaccines
usually have only mild side effects and that the risks of serious adverse
events (for example, death or life-threatening illness) are very low (Smith
2015). Vaccine refusers commonly believe that vaccines often cause seri-
ous disorders (including autism), damage one’s immune system, degrade
one’s genetic code, or place one’s body under unacceptable forms of gov-
ernment surveillance or control (Dubé et al. 2013). Someone who intends
to free ride aims to avoid paying a reasonable price for a public good. But
many vaccine refusers think that vaccination is dangerous and that it
would be unreasonable to ask them to vaccinate. Such people conceive of
vaccination choices as a matter of avoiding or acquiescing to significant
harms, rather than as a matter of whether or not to contribute to a public
good from which they benefit.
III.II. Costs and Benefits
Vaccine refusal also usually fails to meet objective criteria for free riding.
First, vaccine refusers are not free riders on community protection, be-
cause it is not possible to both contribute to and benefit from community
protection. A free rider benefits from a public good to which they could
also contribute. When free riding is immoral, free riders should also con-
tribute to the public goods from which they benefit. The way to contribute
to community protection is to possess individual immunity, either
through vaccination or by recovering from a disease. But people who
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possess individual immunity do not (and indeed, cannot) rely on commu-
nity protection to protect themselves from the diseases against which
they have individual immunity. They rely on individual immunity. Accord-
ingly, someone who contributes to community protection cannot also
benefit from it. Consequently, someone who does not contribute to com-
munity protectionfor example, by refusing vaccinesis not a free rider.
Second, free riding is individually rational, but vaccine refusal is not.
Vaccination almost always promotes the interests of the vaccinated indi-
vidual, even at very high levels of community protection. Since the costs
of vaccination are generally negligiblefor example, serious complica-
tions are exceedingly rare (Spencer, Trondsen Pawlowski, and Thomas
2017)—it is almost always in a person’s interest to vaccinate, even when
community protection makes their odds of infection very low. Consider
the fact that community protection against some vaccine-preventable in-
fections requires very high levels of population-level immunity, such that
even universal vaccination with very effective vaccines may still leave
someone vulnerable to exposure (and therefore make it rational to be vac-
cinated). For example, roughly 95% of the population needs to be individ-
ually immune to measles to eliminate outbreaks (Gay 2004; Moss and Stre-
bel 2011), while only 95% of people fully vaccinated against measles have
individual immunity (Demicheli et al. 2012), so that communities with less
than 100% measles vaccine uptake remain at risk for measles outbreaks,
and therefore individual vaccination against measles is almost always ra-
tional (Bester 2017). More importantly, it is very difficult to know one’s
risk of being exposed to a vaccine-preventable infection, even if reliable
community-wide immunization rates are available. Outbreaks commonly
appear in small geographically clustered groups of under-vaccinated per-
sons (Omer et al. 2008; Phadke et al. 2016), and it can be all but impossible
to identify and avoid such groups. In contrast, vaccination reliably gener-
ates individual immunity at negligible costs. Notably, attempts to model
vaccine refusal as an instance of free riding sometimes presume that in-
dividuals can make reliable predictions about the proportion of immune
individuals in the groups they interact with (for example, Betsch, Böhm,
and Korn 2013). Yet, it seems highly unlikely that most vaccine refusers
possess (or even could possess) such knowledge.
IV. ‘FREE RIDING AND POLICY INTERVENTIONS
If policy responses to vaccine refusal are to be effective and ethically jus-
tified, then they should be based on an accurate understanding of vaccine
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refusal. The claim that vaccine refusers are free riders may lead to policy
proposals that are ineffective or morally unjustified.
IV.I. Incentives and Pro-Vaccine Interventions
There are a set of standard interventions for solving free riding problems
(Buttenheim and Asch 2013). These include offering economic incentives
for cooperation (or disincentives for defection), restricting defectors’ ac-
cess to other goods, invoking or creating social norms to pressure indi-
viduals to cooperate, or using state coercion. These enforcement mecha-
nisms shift the relevant payoffs in ways that incentivise potential free
riders to cooperate, instead of defect, by making it rational for would-be
free riders to contribute (Buttenheim and Asch 2013).
If vaccine refusal were a free rider problem, then one way to encour-
age vaccination would be to slightly shift the perceived payoffs of poten-
tial vaccine refusers. Governments should be able to avoid vaccine refusal
with small (or even trivial) amounts of incentives or disincentives. Recall
that actual free riders acknowledge the value of the public good they en-
joy but refuse to pay the small cost of contributing to that good when
they can get away with not incurring the cost. A government could there-
fore overcome ‘free rider vaccine refusal’ if it increased the costs of vac-
cine refusal so that those costs were somewhat higher than the costs of
vaccination. This means that placing small additional burdens on vaccine
refusers should lead to overcoming vaccine refusal that results from sub-
jective free riding.
The evidence is not consistent with the hypothesis that the behavior
of most vaccine refusers can be changed by making small modifications
to their incentives. For example, many countries have recently adopted or
revised childhood vaccine mandates as a way of providing additional in-
centives for vaccination or of disincentivizing vaccine refusal. For exam-
ple, Australia’s federal government withholds state payments to parents
who do not vaccinate their children (‘No Jab, No Pay’), while their state
governments prevent unvaccinated children from being enrolled in child-
care (‘No Jab, No Play’) (Attwell et al. 2018). All US states require children
to be vaccinated to enroll in school, and many states have recently made
those enrollment mandates more difficult to escape, for example, by elim-
inating nonmedical exemptions or imposing burdensome administrative
procedures (National Conference of State Legislatures 2021). Other polit-
ical communities, like Italy, have decided to fine parents who do not vac-
cinate their children (Vaz et al. 2020).
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These kinds of policy changes sometimes somewhat increase vaccina-
tion rates or decrease nonmedical exemption rates (Omer et al. 2012;
Navin, Largent, and McCright 2020). That is not evidence that the parents
who change their minds in the face of such changed payoffs are free rid-
erswe have already presented evidence to motivate skepticism about
that conclusionbut the number of parents who do change their behav-
iors clearly identifies a ceiling for the maximum number of possible free
riders among vaccine refusers. Even if we supposed that every parent who
changed their vaccination behavior in the face of changes in their incen-
tive structure were a free rider, then the evidence suggests that perhaps
around a third of parents could possibly be free ridersthat is about the
maximum number of vaccine refusers who seem willing to change their
behavior in the face of substantial changes to their incentives. Notably,
even quite serious penalties seem insufficient to change the behavior of
many vaccine refusers. For example, Delamater and colleagues (2019)
found that eliminating nonmedical exemptions in California caused few
parents to vaccinate their children. In fact, the positive results of that
policy change were almost entirely a consequence of better administrative
oversight and record-keeping, or were offset by corresponding increases
in medical exemptions or the enrollment of children not in compliance
with immunization requirements. Many thousands of California parents
allowed their children to be denied access to public or private schools, or
to be prevented from participating in group homeschooling activities ra-
ther than be vaccinated. This is not the profile of a free rider.
Pro-vaccination policies that are likely to overcome free riding behav-
ior, especially subjective free riding behavior, are unlikely to be as effec-
tive against someone who refuses vaccines because they believe vaccines
are ineffective or dangerous. If someone does not think that community
protection is valuable, or if they think vaccination is a grave risk to their
health, then small changes to their incentive structure are unlikely to
change their minds. Relying on a free rider model of the attitudes and
motivations of vaccine refusers may therefore encourage unjustified op-
timism that vaccine refusal can be overcome with minimally invasive in-
terventions.
IV.II. Ethical Justifications for Pro-Vaccine Interventions
The mere fact that community protection is a public good does not, by
itself, justify government coercion (Bernstein and Randall 2020), but the
substantial individual and collective benefits of community protection
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strongly favor government efforts to promote vaccination (Brennan 2018;
Flanigan 2014; Giubilini and Savulescu 2019; Giubilini 2019, 2020; Navin
2016; Pierik 2018). If vaccine refusal were objectively a form of free riding,
then one weighty ethical reason for societies to promote vaccination
would be to promote fairness in the distributions of benefits and burdens
associated with mass immunization. The people who benefit from com-
munity protection should be incentivized or even compelled to contribute
to community protection, rather than be allowed to unfairly free ride on
the socially productive contributions of others, as long as they can do so
at a reasonable cost to themselves.
But vaccine refusers are not objectively free riders, even though some
of them may think they are free riding, as in the case of Dr. Bob Sears’
patients we discussed above. The goal of pro-vaccination policies, there-
fore, should not be to punish people for free riding, that is, to make sure
that they ‘pay’ for the benefits that they enjoy from community protec-
tion. As we argued above, it is not possible both to contribute to and to
benefit from community protection. Inasmuch as fairness plays a role in
ethical arguments for pro-vaccination policies, it should be to make sure
that there is a fair distribution of labor among the members of society
who have a duty to protect others from harm (Giubilini, Douglas, and
Savulescu 2018). That is, fairness in vaccination behavior is about doing
one’s part to help others. It is about being a contributor to community
protection, rather than a beneficiary of it, whenever one is reasonably able
to do so. But fairness with respect to vaccination is not about ensuring
that one is paying for the public goods they are benefiting from: this is
not possible.
Aside from the fact that vaccine refusal is not objectively a free rider
problem, it also matters for an ethical analysis that vaccine refusers are
rarely subjectively free riders. Vaccine refusers usually do not think they
are acting unfairly. They do not believe they are taking advantage of a
public good that they could also be contributing to. Instead, they think
that (almost) everyone would be better off if they refused vaccines. So,
inasmuch as vaccination policies aim to punish vaccine refusers for their
unethical behavior, it would be incorrect to focus on refusers’ supposed
intentions to free ride. Relatedly, inasmuch as vaccine advocates express
anger at vaccine refusers for (what they believe to be) unfair free riding
(Bernstein 2021), those moral emotions are not entirely apt. Vaccine re-
fusers seem to be motivated by ordinary ideas about avoiding serious
risks to their health based on false beliefs about the costs and benefits of
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vaccination and about the risks of vaccine-preventable infections. We
acknowledge that vaccine refusers may sometimes be morally responsible
for these false beliefs and that they may be acting unfairly, but their moral
failure is not the straightforward unfairness of free riding.
V. CONCLUSION
Many people have endorsed pro-vaccination interventions or made ethical
arguments about vaccine refusal that presume vaccine refusers are free
riders. We have argued that vaccine refusal is not an instance of free rid-
ing and that few vaccine refusers believe themselves to be free riding.
Accordingly, effective policy interventions and apt ethical judgments
about vaccine refusal will need to rely on other explanations for why peo-
ple sometimes refuse vaccines.
If those who study vaccine refusal want to introduce game-theoretic
models to explain this phenomenon, then perhaps they should turn away
from free rider models and consider embracing information problem
models. The core dynamics of information problem game-theoretic mod-
els is that participants in the game are not fully aware of the ‘rules’ of the
game, for example, who else is playing, what each participant’s interests
are, and what actions have been taken previously (Jones 1977). Partici-
pants must therefore make educated guesses about the best course of
action, rather than calculate a deterministic result. In light of the promi-
nent role that false beliefs play in the decisions of vaccine refusers, such
models may present more accurate depictions of the objective and sub-
jective attributes of vaccine refusal than free rider models do.
REFERENCES
Anderson, Evan J., Michael A. Daugherty, Larry K. Pickering, Walter A. Orenstein, and
Ram Yogev. 2018. “Protecting the Community through Child Vaccination.” Clinical
Infectious Diseases 67 (3): 464471.
Attwell, Katie, Mark C. Navin, Pier Luigi Lopalco, Christine Jestin, Sabine Reiter, and Saad
B. Omer. 2018. “Recent Vaccine Mandates in the United States, Europe and Australia:
A Comparative Study.” Vaccine 36 (48): 73777384.
Bauch, Chris T., Samit Bhattacharyya, and Robert F. Ball. 2010. “Rapid Emergence of Free-
Riding Behavior in New Pediatric Immunization Programs.” PLoS ONE 5 (9): e12594.
Bernstein, Justin. 2021. “Anti-Vaxxers, Anti-Anti-Vaxxers, Fairness, and Anger.” Kennedy
Institute of Ethics Journal 31 (1): 1752.
Bernstein, Justin, and Pierce Randall. 2020. “Against the Public Goods Conception of
Public Health.” Public Health Ethics 13 (3): 225233.
Bester, Johan Christiaan. 2017. “Measles Vaccination Is Best for Children: The Argument
for Relying on Herd Immunity Fails.” Journal of Bioethical Inquiry 14 (3): 375384.
BRADLEY AND NAVIN / VACCINE REFUSAL IS NOT FREE RIDING
VOLUME 14, ISSUE 1, SPRING 2021
178
Betsch, Cornelia, Robert Böhm, and Lars Korn. 2013. “Inviting Free-Riders or Appealing
to Prosocial Behavior? Game-Theoretical Reflections on Communicating Herd Im-
munity in Vaccine Advocacy.” Health Psychology 32 (9): 978985.
Betsch, Cornelia, Robert Böhm, Lars Korn, and Cindy Holtmann. 2017. “On the Benefits
of Explaining Herd Immunity in Vaccine Advocacy.” Nature Human Behaviour 1 (3):
0056.
Brennan, Jason. 2018. “A Libertarian Case for Mandatory Vaccination.” Journal of Medical
Ethics 44 (1): 3743.
Breslow, Jason. 2020. “Fauci: Mixed Messaging on Masks Set U.S. Public Health Response
Back.” National Public Radio, July 1, 2020. https://www.npr.org/sections/health-
shots/2020/07/01/886299190/it-does-not-have-to-be-100-000-cases-a-day-fauci-
urges-u-s-to-follow-guidelines.
Buttenheim, Alison M., and David A. Asch. 2013. “Making Vaccine Refusal Less of a Free
Ride.” Human Vaccines & Immunotherapeutics 9 (12): 26742675.
Clarke, Steve, Alberto Giubilini, and Mary Jean Walker. 2017. “Conscientious Objection
to Vaccination.” Bioethics 31 (3): 155161.
Cullity, Garrett. 1995. “Moral Free Riding.” Philosophy & Public Affairs 24 (1): 334.
Dawson, Angus. 2007. “Herd Protection as a Public Good: Vaccination and Our Obliga-
tions to Others.” In Ethics, Prevention, and Public Health, edited by Angus Dawson
and Marcel F. Verweij, 160178. Oxford: Clarendon Press.
Delamater, Paul L., S. Cassandra Pingali, Alison M. Buttenheim, Daniel A. Salmon, Nicola
P. Klein, and Saad B. Omer. 2019. “Elimination of Nonmedical Immunization Exemp-
tions in California and School-Entry Vaccine Status.” Pediatrics 143 (6): e20183301.
Demicheli, Vittorio, Alessandro Rivetti, Maria Grazia Debalini, and Carlo Di Pietrantonj.
2012. “Vaccines for Measles, Mumps, and Rubella in Children.” Cochrane Database
of Systematic Reviews 2: CD004407.
Dubé, Eve, Caroline Laberge, Maryse Guay, Paul Bramadat, Réal Roy, and Julie A. Bet-
tinger. 2013. “Vaccine Hesitancy: An Overview.” Human Vaccines & Immunothera-
peutics 9 (8): 17631773.
Flanigan, Jessica. 2014. “A Defense of Compulsory Vaccination.” HEC Forum 26 (2): 5
25.
Freeman, Daniel, Bao S. Loe, Andrew Chadwick, Cristian Vaccari, Felicity Waite, Laina
Rosebrock, Lucy Jenner et al. Forthcoming. “COVID-19 Vaccine Hesitancy in the UK:
The Oxford Coronavirus Explanations, Attitudes, and Narratives Survey (Oceans) II.”
Psychological Medicine.
Gay, Nigel J. 2004. “The Theory of Measles Elimination: Implications for the Design of
Elimination Strategies.” The Journal of Infectious Diseases 189 (Supplement_1): S27
S35.
Giubilini, Alberto. 2019. The Ethics of Vaccination. Cham: Palgrave Macmillan.
Giubilini, Alberto. 2020. “An Argument for Compulsory Vaccination: The Taxation Anal-
ogy.” Journal of Applied Philosophy 37 (3): 446466.
Giubilini, Alberto, and Julian Savulescu. 2019. “Vaccination, Risks, and Freedom: The
Seat Belt Analogy.” Public Health Ethics 12 (3): 237249.
Giubilini, Alberto, Thomas Douglas, and Julian Savulescu. 2017. “Liberty, Fairness and
the ‘Contribution Model’ for Non-Medical Vaccine Exemption Policies: A Reply to
Navin and Largent.” Public Health Ethics 10 (3): 235240.
BRADLEY AND NAVIN / VACCINE REFUSAL IS NOT FREE RIDING
ERASMUS JOURNAL FOR PHILOSOPHY AND ECONOMICS
179
Giubilini, Alberto, Thomas Douglas, and Julian Savulescu. 2018. “The Moral Obligation
to Be Vaccinated: Utilitarianism, Contractualism, and Collective Easy Rescue.” Med-
icine, Health Care and Philosophy 21 (4): 547560.
Glanz, James, Benedict Carey, Josh Holder, Derek Watkins, Jennifer Valentino-DeVries,
Rick Rojas, and Lauren Leatherby. 2020. “Where America Didn’t Stay Home Even as
the Virus Spread.” The New York Times, April 2, 2020. https://www.nytimes.com/in-
teractive/2020/04/02/us/coronavirus-social-distancing.html.
Global Polio Eradication Initiative. n.d. “Polio-Free Countries.” Global Polio Eradication
Initiative. Accessed January 23, 2021. https://polioeradication.org/where-we-work/
polio-free-countries/.
Hardin, Russell. 1971. “Collective Action as an Agreeable n-Prisoners’ Dilemma.” Behav-
ioral Science 16 (5): 472481.
Harmsen, Irene A., Liesbeth Mollema, Robert A. C. Ruiter, Theo G. W. Paulussen, Hester
E. de Melker, and Gerjo Kok. 2013. “Why Parents Refuse Childhood Vaccination: A
Qualitative Study Using Online Focus Groups.” BMC Public Health 13 (1): 1183.
Hendrix, Kristin S., Lynne A. Sturm, Gregory D. Zimet, and Eric M. Meslin. 2016. “Ethics
and Childhood Vaccination Policy in the United States.” American Journal of Public
Health 106 (2): 273278.
Ibuka, Yoko, Meng Li, Jeffrey Vietri, Gretchen B. Chapman, and Alison P. Galvani. 2014.
“Free-Riding Behavior in Vaccination Decisions: An Experimental Study.” PLoS ONE
9 (1): e87164.
Jacobson, Robert M., Jennifer L. St. Sauver, and Lila J. Finney Rutten. 2015. “Vaccine Hes-
itancy.” Concise Review for Clinicians 90 (11): 15621568.
Jones, Neil D. 1977. “Blindfold Games are Harder than Games with Perfect Information.”
DAIMI Report No. PB80. Department of Computer Science, University of Aarhus,
Denmark.
Lazarus, Jeffrey V., Scott C. Ratzan, Adam Palayew, Lawrence O. Gostin, Heidi J. Larson,
Kenneth Rabin, Spencer Kimball, and Ayman El-Mohandes. 2021. “A Global Survey
of Potential Acceptance of a COVID-19 Vaccine.” Nature Medicine 27 (2): 225228.
May, Thomas, and Ross D. Silverman. 2005. “Free-Riding, Fairness, and the Rights of
Minority Groups in Exemption from Mandatory Childhood Vaccination.” Human
Vaccines 1 (1): 1215.
Moss, William J., and Peter Strebel. 2011. “Biological Feasibility of Measles Eradication.”
The Journal of Infectious Diseases 204 (Supplement_1): S47S53.
National Conference of State Legislatures. 2021. “States with Religious and Philosophical
Exemptions from School Immunization Requirements.” National Conference of
State Legislatures. Accessed February 11, 2021. https://www.ncsl.org/research/
health/school-immunization-exemption-state-laws.aspx.
Navin, Mark. 2016. Values and Vaccine Refusal: Hard Questions in Ethics, Epistemology,
and Health Care. New York, NY: Routledge.
Navin, Mark C., Mark A. Largent, and Aaron M. McCright. 2020. “Efficient Burdens De-
crease Nonmedical Exemption Rates: A Cross-County Comparison of Michigan’s
Vaccination Waiver Education Efforts.” Preventive Medicine Reports 17: 101049.
Olson, Jr., Mancur. 1965. The Logic of Collective Action: Public Goods and the Theory of
Groups. Cambridge, MA: Harvard University Press.
BRADLEY AND NAVIN / VACCINE REFUSAL IS NOT FREE RIDING
VOLUME 14, ISSUE 1, SPRING 2021
180
Omer, Saad B., Jennifer L. Richards, Michelle Ward, and Robert A. Bednarczyk. 2012.
“Vaccination Policies and Rates of Exemption from Immunization, 2005–2011.” The
New England Journal of Medicine 367 (12): 11701171.
Omer, Saad B., Kyle S. Enger, Lawrence H. Moulton, Neal A. Halsey, Shannon Stokley, and
Daniel A. Salmon. 2008. “Geographic Clustering of Nonmedical Exemptions to
School Immunization Requirements and Associations with Geographic Clustering
of Pertussis.” American Journal of Epidemiology 168 (12): 13891396.
Phadke, Varun K., Robert A. Bednarczyk, Daniel A. Salmon, and Saad B. Omer. 2016.
“Association Between Vaccine Refusal and Vaccine-Preventable Diseases in the
United States: A Review of Measles and Pertussis.” JAMA 315 (11): 11491158.
Pierik, Roland. 2018. “Mandatory Vaccination: An Unqualified Defence.” Journal of Ap-
plied Philosophy 35 (2): 381398.
Quadri-Sheriff, Maheen, Kristin S. Hendrix, Stephen M. Downs, Lynne A. Sturm, Gregory
D. Zimet, and S. Maria E. Finnell. 2012. “The Role of Herd Immunity in Parents’ De-
cision to Vaccinate Children: A Systematic Review.” Pediatrics 130 (3): 522530.
Salmon, Daniel A., and Andrew W. Siegel. 2001. “Religious and Philosophical Exemptions
from Vaccination Requirements and Lessons Learned from Conscientious Objectors
from Conscription.” Public Health Reports 116 (4): 289295.
Schröder-Bäck, Peter, Helmut Brand, Ixhel Escamilla, John K. Davies, Caroline Hall, Kieran
Hickey, Eleni Jelastopulu, Reli Mechtler, and Jaroslav Volf. 2009. “Ethical Evaluation
of Compulsory Measles Immunisation as a Benchmark for Good Health Management
in the European Union.” Central European Journal of Public Health 17 (4): 183186.
Sears, Robert W. 2007. The Vaccine Book: Making the Right Decision for Your Child. New
York, NY: Little, Brown and Co.
Siegal, Gil, Neomi Siegal, and Richard J. Bonnie. 2009. “An Account of Collective Actions
in Public Health.” American Journal of Public Health 99 (9): 15831587.
Smith, Michael. 2015. “Vaccine Safety: Medical Contraindications, Myths, and Risk Com-
munication.” Pediatrics in Review 36 (6): 227238.
Sobo, Elisa J. 2016. “What Is Herd Immunity, and How Does It Relate to Pediatric Vac-
cination Uptake? US Parent Perspectives.” Social Science & Medicine 165: 187195.
Spencer, Jeanne P., Ruth H. Trondsen Pawlowski, and Stephanie Thomas. 2017. “Vaccine
Adverse Events: Separating Myth from Reality.” American Family Physician 95 (12):
786794.
van den Hoven, Mariëtte. 2012. “Why One Should Do One’s Bit: Thinking About Free
Riding in the Context of Public Health Ethics.” Public Health Ethics 5 (2): 154160.
van Rooij, Benjamin, Anne Leonore de Bruijn, Chris Reinders Folmer, Emmeke Barbara
Kooistra, Malouke Esra Kuiper, Megan Brownlee, Elke Olthuis, and Adam Fine. 2020.
“Compliance with COVID-19 Mitigation Measures in the United States.” Amsterdam
Law School Research Paper No. 202021. Social Science Research Network, Roches-
ter, NY.
Vaz, Olivia M., Mallory K. Ellingson, Paul Weiss, Samuel M. Jenness, Azucena Bardají,
Robert A. Bednarczyk, and Saad B. Omer. 2020. “Mandatory Vaccination in Europe.”
Pediatrics 145 (2): e20190620.
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Ethan Bradley is an undergraduate student of philosophy and political
science at Oakland University (Rochester, MI, USA).
Contact e-mail: <embradley@oakland.edu>
Mark Navin is professor and chair of philosophy at Oakland University
(Rochester, MI, USA).
Contact e-mail: <navin@oakland.edu>
... As expected, higher costs of vaccines (both monetary and in terms of side-effects) decreased vaccination intention (see [61,62]). We found no effect of immunization status of the surrounding social group, and thus no empirical evidence for the 'free-riding' hypotheses (see also the discussion in reference [63]) or, conversely, for a strong influence of social conformity [46]. The only positive psychometric predictor of heightened vaccination intention was higher empathy with those most vulnerable to the pandemic. ...
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Containing a pandemic requires that individuals adhere to measures such as wearing face-masks and get vaccinated. Therefore, identifying predictors and motives for both behaviors is of importance. Here, we study the decisions made by a cross-national sample in randomized hypothetical scenarios during the COVID-19 pandemic. Our results show that mask-wearing was predicted by empathic tendencies, germ aversion, and higher age, whilst belief in misinformation and presentation of an interaction partner as a family member lowered the safety standards. The main motives associated with taking the mask off included: rationalization, facilitating interaction, and comfort. Vaccination intention was positively predicted by empathy, and negatively predicted by belief in misinformation and higher costs of the vaccine. We found no effect of immunization status of the surrounding social group. The most common motive for vaccination was protection of oneself and others, whereas undecided and anti-vaccine groups reported doubts about the effectiveness and fear of side effects. Together, we identify main social and psychological predictors and motives of mask-wearing behavior and vaccination intention. The results highlight the importance of social context for mask-wearing, easy access to vaccines, empathy, and trust in publicly distributed information.
... However, vaccine-hesitant people worry about possible future and long-term effects induced by the fast development of these vaccines [32], especially for new vaccine technology such as mRNA and viral vector [33], when developing a vaccine takes 15 years on average [34]. Such post-injection anxiety [35] has not yet received an appropriate response. Additionally, these vaccines had only obtained emergency use authorisation without full approval [36] prior to August 2021 for COMIRNATY ® , for which they bypassed the animal studies used to understand the action mechanism and the ability of the virus to resist the vaccine [37,38]. ...
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In a recent article, Ethan Bradley and Mark Navin (2021) argue that vaccine refusal is not akin to free riding. Here, I defend one connection between vaccine refusal and free riding and suggest that, when viewed in conjunction with their other arguments, this might constitute a reason to mandate Covid-19 vaccination.
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I argue that there are significant moral reasons in addition to harm prevention for making vaccination against certain common infectious diseases compulsory. My argument is based on an analogy between vaccine refusal and tax evasion. First, I discuss some of the arguments for compulsory vaccination that are based on considerations of the risk of harm that the non‐vaccinated would pose on others; I will suggest that the strength of such arguments is contingent upon circumstances and that in order to provide the strongest defence possible of compulsory vaccination, such arguments need to be supplemented by additional arguments. I will then offer my additional argument for compulsory vaccination: I will argue that in both cases of vaccine refusal and of tax evasion individuals fail to make their fair contribution to important social and public goods, regardless of whether each individual contribution ‘makes a difference’. While fairness considerations have sometimes been used to support a moral duty to vaccinate, they have not been appealed to in order to argue for a legal duty to vaccinate. I will suggest that this is due, among other things, to a misapplication of the principle of the least restrictive alternative in public health. Finally, I will address nine possible objections to my argument.
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In a paper recently published in this journal, Navin and Largent argue in favour of a type of policy to regulate non-medical exemptions from childhood vaccination which they call ‘Inconvenience’. This policy makes it burdensome for parents to obtain an exemption to child vaccination, for example, by requiring parents to attend immunization education sessions and to complete an application form to receive a waiver. Navin and Largent argue that this policy is preferable to ‘Eliminationism’, i.e. to policies that do not allow non-medical exemptions, because Inconvenience has been shown to maintain exemption rates low while not harming parents by forcing them to do something that goes against their beliefs. We argue that it is at least doubtful that Inconvenience is ethically preferable to Eliminationism: while the latter disregards the value of liberty, Inconvenience disregards the value of fairness in the distribution of the burdens entailed by the preservation of a public good like herd immunity. We propose a variant of Inconvenience, which we call ‘Contribution’, which we think is preferable to the versions of Inconvenience discussed by Navin and Largent in that it successfully strikes a balance between the values of parents’ liberty, fairness and expected utility.
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Public health ethicists face two difficult questions. First, what makes something a matter of public health? While protecting citizens from outbreaks of communicable diseases is clearly a matter of public health, is the same true of policies that aim to reduce obesity, gun violence or political corruption? Second, what should the scope of the government’s authority be in promoting public health? May government enact public health policies some citizens reasonably object to or policies that are paternalistic? Recently, some theorists have attempted to address these questions by arguing that something is a matter of public health if and only if it involves a health-related public good, such as clean water or herd immunity. Relatedly, they have argued that appeals to the promotion of public health should only be used to justify the provision of health-related public goods. This public goods conception of public health (PGC) is meant to enjoy advantages over its rivals in three respects: it provides a better definition of public health than rival views, it respects moral disagreement, and it avoids licensing objectionably paternalistic public health policies. We argue, however, that the PGC does just as poorly, or worse, than its rivals in all three respects.
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Background and objectives: California implemented Senate Bill 277 (SB277) in 2016, becoming the first state in nearly 30 years to eliminate nonmedical exemptions from immunization requirements for schoolchildren. Our objectives were to determine (1) the impacts of SB277 on the percentage of kindergarteners entering school not up-to-date on vaccinations and (2) if geographic patterns of vaccine refusal persisted after the implementation of the new law. Methods: At the state level, we analyzed the magnitude and composition of the population of kindergarteners not up-to-date on vaccinations before and after the implementation of SB277. We assessed correlations between previous geographic patterns of nonmedical exemptions and patterns of the remaining entry mechanisms for kindergarteners not up-to-date after the law's implementation. Results: In the first year after SB277 was implemented, the percentage of kindergartners entering school not up-to-date on vaccinations decreased from 7.15% to 4.42%. The conditional entrance rate fell from 4.43% to 1.91%, accounting for much of this decrease. Other entry mechanisms for students not up-to-date, including medical exemptions and exemptions for independent study or homeschooled students, largely replaced the decrease in the personal belief exemption rate from 2.37% to 0.56%. In the second year, the percentage of kindergartners not up-to-date increased by 0.45%, despite additional reductions in conditional entrants and personal belief exemptions. The correlational analysis revealed that previous geographic patterns of vaccine refusal persisted after the law's implementation. Conclusions: Although the percentage of incoming kindergarteners up-to-date on vaccinations in California increased after the implementation of SB277, we found evidence for a replacement effect.