Y. Tony Yang, Sc.D., LL.M., M.P.H., and Ross D. Silverman, J.D., M.P.H.
Department of Health Administration and Policy, George Mason University, Fairfax, VA (Y.T.Y.); and the Department of Health Policy and Management, Fairbanks School of Public Health, and McKinney School of Law, Indiana University, Indianapolis (R.D.S.)
If a state allows parents to obtain religious exemptions from vaccination requirements for school entry, can it temporarily exclude unvaccinated children from school during an outbreak of a vaccine-preventable illness without violating the family's constitutional rights? If parents refuse to vaccinate their children, what can physicians legally and ethically do to protect other patients in their practice from exposure to vaccine-preventable illnesses?
In January 2015, a federal appeals court answered the former question with regard to New York State law on immunization for school enrollment, upholding the state's authority to bar unvaccinated children from school during outbreaks, even if doing so overrides a family's religious freedom with regard to vaccination.  Physicians nationwide are facing the latter question as they respond to the measles outbreak that began at Disneyland in California in December 2014 and had spread to at least 17 states, Canada and Mexico by late February.  Both questions invoke the legal and moral authority to use a classic public health measure known as social distancing to attempt to mitigate the spread of an infectious disease (see table: Examples of Social Distancing Measures for Controlling Vaccine-Preventable Illnesses.). Nevertheless, trade-offs between personal freedom and public health are implicit in such measures. Governments and physicians employing social distancing policies must give careful and systematic attention to the ethical and legal issues.
Under the Constitution, states have police power to protect the public's health, welfare and safety. A long-standing use of this authority is to protect communities from risks related to vaccine-preventable illnesses. In addition, when an infectious-disease outbreak occurs, states may use their police power to interrupt further transmission of the disease by restricting the movement of individuals. All states have incorporated this concept of social distancing into their school immunization laws. Schools can prohibit an unvaccinated child, who is more susceptible to acquiring highly infectious vaccine-preventable illness and more likely to become a carrier and vector for it, from coming to school until the danger subsides. Such measures, coupled with ready availability of vaccines, reduce the potential spread of serious disease in a vulnerable and tightly packed community.
In the recent case, Phillips v. City of New York, New York's social distancing policy was challenged after the children of two families with religiously grounded vaccination exemptions were excluded from school for a period of time after a fellow student tested positive for chickenpox.  Finding the vaccine policy "well within the State's police power," the Second Circuit Court reiterated the Supreme Court decision in the 1905 case Jacobson v. Massachusetts, which clearly found vaccine mandates constitutional.  The court also cited the Supreme Court decision in a 1944 case, Prince v. Massachusetts, which supported limits to religious freedom if an individual's expression of liberty risked putting his or her child or the community at risk for harm or ill health. 
The scope of state public health laws, and state immunization policies in particular, may continue to be challenged. However, the Phillips case, with its focus on a core First Amendment right and a relatively mild vaccine-preventable illness, affirms the long-held axiom that the state can use its police power in ways that supersede religious and parental preferences, and somewhat burden individuals, to uphold our societal responsibility to use reasonable measures to protect against infectious-disease outbreaks.
Although exclusion measures represent a legitimate use of police power when a reasonable health threat exists, more subtle legal and logistic questions remain. Who -- state health departments, school principals or both -- has the power to order school exclusion, using what criteria, and for what period? What disease threats should trigger school exclusion, and how should thresholds vary among diseases? What should the penalties be for noncompliance? Clearly, standards for necessity and proportionality should be followed, including seeking voluntary compliance and avoidance of premature imposition of exclusions, extension of exclusions beyond the end of a crisis and imposition of restrictions that are ineffective at reducing transmission. Furthermore, the cost of restrictive policies will be borne most heavily by people with the fewest resources, so errant social distancing actions have implications for distributive justice.
Meanwhile, the court's discussion in the Phillips case of the deference that courts give to legislative determinations regarding a state's use of its police power reveals another way in which public health could be imperiled. The plaintiff families tried unsuccessfully to get the court to consider whether vaccines cause the public more harm than good. In its decision not to address that question, the court pointed again to Jacobson, stating in part that "that is a determination for the legislature."  The implication is that if a legislature were convinced by inaccurate information, it could enact harmful public health policies founded on that misinformation. This possibility reinforces an important responsibility of public health experts to actively engage in the policymaking process, educating legislators and regulators about the health and safety benefits of public policy informed by robust science.
Beyond participating in such educational efforts, what can individual physicians do to help with social distancing to limit the spread of vaccine-preventable illnesses? Although physicians are legally able to deny services to unvaccinated patients in most situations, most medical professionals would probably agree with the American Academy of Pediatrics that such an extreme option should be avoided.  Such an action would deny an unvaccinated child access to a range of medical services and ongoing health education and would sow distrust in not only the family refused care, but also the family's broader social network.
Instead, providers may consider other alternatives, including but not limited to establishing triage protocols for unvaccinated children (e.g., preliminary teleconsults before clinic presentation) and reserving appointments at the end of clinic hours. Such measures may enable physicians to continue their respectful and trust-instilling dialogue with parents, ensure children's ongoing access to care, and in time, increase the likelihood that a hesitant parent may reconsider opposition to this important health intervention.
Efforts to control vaccine-preventable illnesses force society to face a number of difficult challenges, many of which transcend the issue of scientific effectiveness. Social distancing measures raise ethical issues central to society's commitment to freedom and social justice. Even when they are effective, social distancing measures can have adverse consequences for economic and civil liberties. At the same time, increased public knowledge of the existence of such measures may lead more vaccine-questioning parents to choose to follow vaccination recommendations. Though social distancing may represent a key public health measure, such infringement of individual rights should be minimized and undertaken only when necessary to protect the public's health.
1. Phillips v. City of New York, No. 14-2156 (2d Cir. 2015).
2. Centers for Disease Control and Prevention. Measles cases and outbreaks (http://www.cdc.gov/measles/cases-outbreaks.html).
3. Jacobson v. Massachusetts, 197 U.S. 11 (1905).
4. Prince v. Massachusetts, 321 U.S. 158, 166-67 (1944).
5. American Academy of Pediatrics. Reaffirmation: responding to parents who refuse immunization for their children. Pediatrics 2013;131:e1696-e1696