Minnesota is receiving national attention for its measles outbreak. As of May 11th, 49 children in Minnesota have already contracted measles in 2017. This is an astonishingly high number: from 2001 to 2016, there were only 46 cases of measles, and that included an outbreak of 26 children in 2011. Using data from the Minnesota Department of Health, the chart below tracks the number of reported cases of measles in Minnesota from 2000 to the present.
The blame is rightly being placed with the anti-vaccination movement. For a decade, Minnesotans, including those in the Somali community, have been fed misinformation that the Measles-Mumps-Rubella (MMR) vaccine causes autism, creating a panic that has dropped vaccination rates in Minnesota to lows not seen in 30 years. Low vaccination rates among toddlers, as well as the rising use of philosophical vaccination exemptions in Minnesota schools, have revived a disease that had been eliminated in the US since 2000. This article will examine the outcomes if these philosophical exemptions were more difficult to obtain.
Measles outbreaks are unprecedented in the United States in modern times. Since the development of the MMR vaccine in the 1970s, national cases of the measles dropped to historic lows throughout the 1980s and 1990s, but have slowly risen in the 2000s. This growth can be tied to British scientist Andrew Wakefield.
In 1998, Wakefield and a dozen other authors published a study in The Lancet that made a controversial claim: the administration of MMR vaccines to children correlated to symptoms of autism. This research pitted anti-vaccination activists and concerned parents against pharmaceutical companies and the scientific explanation of autism of the day (refrigerator mothers…); however, replicative studies could not find a correlation between the MMR vaccine and autism, and reports of conflicts of interest and the lack of peer review led to the study’s retraction.
Wakefield was also stripped of his ability to practice medicine in the UK. He has since moved to the United States to continue his research and gives paid speeches to various organizations and communities, including the Minneapolis Somali community in 2011. His work, despite its lack of evidence, has provided a platform for anti-vaccination groups to create uncertainty about the safety of MMR and other vaccines. Parents can seek exemptions for their children and send them to school and/or day care without vaccinations. Without the vaccines, these children become vulnerable to contract vaccine preventable illnesses, as well as pass those diseases on to other vulnerable people (like infants, patients receiving chemotherapy, the elderly, etc.). With the current outbreak already infecting 51 people (with no indications of slowing down), we should consider the merits of these exemptions and whether they should be more difficult to obtain.
In terms of public health, Mississippi is rarely considered a leader, but the state excels in vaccination rates. Part of the reason for this success is the state only provides medical exemptions for vaccines; no philosophical or conscientious exemptions exist in Mississippi. The results speak for themselves: 99.7% of kindergartners are vaccinated, and there have not been any cases of measles in Mississippi in over a decade. Compare that with Minnesota, which allows for over 1,000 philosophical exemptions to all vaccines annually, in addition to medical exemptions. The state has seen 48 cases of measles so far this year, and an additional 56 cases since 1997. It is easy to see how communities with clusters of unvaccinated children are at a heightened risk for contracting a highly contagious illness like measles. In addition, it is important to note that rather than being a problem specific to the Somali community, this impacts everyone: many of the highest rates of unvaccinated children are in rural or wealthy suburban neighborhoods.
The logic of the medical vaccine exemption is universally supported. Medical exemptions are meant for those who are either immuno-compromised or are allergic to a component of the vaccine (eggs, for example). If a person could be killed because their immune system can’t fight against even a weakened version of a disease, they are exempt. This requires almost everyone else around them to vaccinate, so they don’t expose unvaccinated people to the disease in question. If enough people in a community are vaccinated, they can essentially prevent those with medical exemptions from contracting the disease. This is called herd immunity.
The percentage of people in a community that needs to be vaccinated to protect everyone varies with the illness. Measles, for example, requires around 94% of people to have immunity to prevent an outbreak. This is a high threshold, but measles is an incredibly contagious airborne illness. Less contagious diseases like polio have herd immunity thresholds in the mid-80s. Of course, if a community only has 42% of children vaccinated, like the Somali community in Minnesota, there is no herd immunity at all.
If medical exemptions were the only type of exemption, and everyone else diligently vaccinated, outbreaks of vaccine-preventable illnesses would end; however, the philosophical exemption allows any parent to exempt their child from vaccines based on their personal beliefs, and in Minnesota, it is incredibly simple to obtain. Philosophical exemptions are designed to protect religious liberties or personal beliefs that clash with vaccine use, but today’s exemptions in Minnesota do not require any vetting of religious affiliation, or any discussion about why the parent wants an exemption. It’s as simple as signing a form and getting it notarized. Given this simplicity, anti-vaccination groups can cast uncertainty and spread misinformation about vaccine safety, pushing parents (who are often scared and trying to protect their child) to delay their vaccine schedules or use philosophical exemptions to keep their children unvaccinated.
The scientific consensus today is that vaccines are safe and unrelated to autism, and clouding the debate with anti-vaccination misinformation only confuses concerned parents and harms children and immune-compromised individuals who rely on everybody else to keep them safe. For those interested in seeing the vaccination rates in their county, school district, and school, follow this link, from the Minnesota Department of Health.