We are in the midst of yet another measles outbreak, and this one is on track to be record breaking. The CDC reports:

From January 1 to April 4, 2019, 465 individual cases of measles have been confirmed in 19 states. This is the second-greatest number of cases reported in the U.S. since measles was eliminated in 2000.

The states that have reported cases to CDC are Arizona, California, Colorado, Connecticut, Florida, Georgia, Illinois, Indiana, Kentucky, Massachusetts, Michigan, Missouri, Nevada, New Hampshire, New Jersey, New York, Oregon, Texas, and Washington.

In 2014 there were a total of 667 cases, making 2019 already the second worst year in a decade, and on track to be the worst since measles was eliminated in the US. The 2014 cases were part of the Disney outbreak that continued into 2015. However the majority were from an unvaccinated Amish community in Ohio.

This year the outbreaks are all in communities where unvaccinated children are clustered. Make no mistake – the evidence is clear that these outbreaks are due to vaccine refusal, to the misinformation campaign of antivaxxers. The rate of vaccine refusal remains low overall in the US, but they do tend to cluster. These are pockets of susceptibility where this highly infectious disease can spread; you can’t hide in the herd.

From 2001-2015 about 70% of the total measles cases in the US were in those who were not vaccinated or had unclear vaccination status. The percentage of cases imported from outside the US decreased from 46.6% in 2001 to 14.7% in 2015, representing the rise of cases originating in the US.

The antivaccine movement kicked into high gear around the turn of the century with the publication of the paper by Wakefield suggesting a link between autism and the MMR vaccine (which covers measles). Even though Wakefield was thoroughly discredited, and the scientific evidence shows no such link, the antivaccine movement has spread. Some credit social media for the ease with which they were able to spread their misinformation.

We predicted that it would take a return of previously eliminated diseases before there would be public pushback against the antivaccine movement, and that is what happened in 2015 after the Disney outbreak. In 2016 California even passed a law banning non-medical exemptions. This worked, sort of, but since then the number of medical exemptions has tripled.

The law just created an industry of unscrupulous doctors giving away medical exemptions. In San Diego one doctor is responsible for one third of the medical exemptions given. They are sometimes just sold to patients, or given with little justification.

Clearly the response to 2014-2015 outbreaks was not sufficient. The antivaxxers just redoubled their efforts and found ways around the new restrictions. We are feeling the result now, with another record-breaking year of measles. And now we are in another political fight between those trying to protect the public health, and a small minority of parents who feel they know better than the consensus of scientific and expert medical opinion.

In Rockland County NY, center of a large outbreak, official have tried to ban unvaccinated students from attending school in an attempt to stem the spread of measles. However, a judge just put a hold on that ban while a lawsuit works its way through the courts. As The Washington Post reports:

But in the days that followed, parents from a private Waldorf school filed a lawsuit that called the ban “arbitrary” and “capricious.” The parents argued that county officials had exceeded their legal authority and that the ban “effectively prohibited their movement and denied them the right to congregate and assemble in public places.”

Yeah – that is the point, to restrict your right to congregate and assemble in public and spread measles. This is a feature, not a bug, of the proposed ban.

At least the recent outbreaks are forcing a public conversation about this issue. While the ethics seems fairly clear, we do want to strike a reasonable balance. It is well accepted, for example, that competent adults have the right to refuse any medical intervention. Parents also have the right to make medical decisions for their children, but the state has a right and a duty to also look after children and may intervene if the parent’s decisions amount to abuse or neglect. This is a reasonable big-picture balance, and the details will be endlessly tweaked and debated in court.

But with vaccines there is a new element to consider – because they affect the entire community, not just the individual. We rely on community immunity, which requires a critical threshold of people to be vaccinated to prevent the spread of an infectious disease. Adequate immunization effectively prevents isolated cases from turning into outbreaks, and outbreaks turning into endemic (self-sustaining) disease.

As we are seeing, even small numbers of vaccine refusers, if the congregate together, can form pockets in which outbreaks occur. Those outbreaks then spread to those who are vaccinated but did not form adequate antibody protection, or have legitimate medical exemptions from vaccines. When your personal decision can affect others in your community, the community has a legitimate stake and can use the legal system to protect itself. You can’t, for example, burn toxic substances on your property because the fumes will affect your neighbors.

As a reaction to the recent measles outbreaks, many states are tightening their laws. Most are simply getting rid of non-medical exemptions for vaccines, a move which we heartily endorse. You can’t simply say that you disagree with the science and choose to make a bad medical decision for the community. Again – there are many analogies to this. We have scientific and legal institutions so that we can make collective decisions for the public good, and we do try to carefully balance personal liberty with the needs of society.

This logic is partly what has lead to the many smoking bans. Your right to smoke is limited by the spread of that smoke into the air that someone else breathes, especially if that smoke causes harm. Similarly, your right to gather together into groups of unvaccinated people can legitimately be limited by the harm this does to the community by increasing the risk of disease outbreaks.

Further, states considering getting rid of non-medical exemptions should learn the lesson from California. You can’t simply leave it up to the discretion of individual practicing physicians, because even one outlier can veto the law by indiscriminately giving out exemptions. There also needs to be a standard in place that is enforced – what counts as a medical exemption? Doctors found to be giving out excessive exemptions should be investigated in the same way that doctors who are found to be writing disproportionate opiate prescriptions are investigated. We already have an enforced standard of care – it just needs to be applied to vaccine exemptions.

We also need to continue public education efforts to stem the flow of misinformation from the antivaccine movement, but I doubt we will ever be able to win that battle sufficiently. Even a small number of people can break the system of protection unless the restrictions are tightened significantly.

We can also look at it this way – antivaxers have been preaching for years that vaccines don’t actually work, that vaccine refusal is not the cause of outbreaks, and that these illnesses are benign anyway. Well – they caused a natural experiment of those claims, and they all failed completely. Vaccine refusal leads directly to outbreaks, because the vaccines work. The evidence is overwhelming, far more than sufficient to use as a basis for public policy.

Politicians now just need to do their jobs, to protect the public health (one of the fundamental missions of government), and not to cave to small special interest groups. These outbreaks do give us a window of opportunity to marshal the political will to craft proper regulations. The antivaxxers have left us no other choice.


Posted by Steven Novella

Founder and currently Executive Editor of Science-Based Medicine Steven Novella, MD is an academic clinical neurologist at the Yale University School of Medicine. He is also the host and producer of the popular weekly science podcast, The Skeptics’ Guide to the Universe, and the author of the NeuroLogicaBlog, a daily blog that covers news and issues in neuroscience, but also general science, scientific skepticism, philosophy of science, critical thinking, and the intersection of science with the media and society. Dr. Novella also has produced two courses with The Great Courses, and published a book on critical thinking - also called The Skeptics Guide to the Universe.