Vaccines have saved hundreds of thousands of lives, and they will prevent 322 million illnesses in those children vaccinated in just the last 20 years. They have lowered the annual number of measles cases worldwide from half a million, prior to 1963, to just 60. Despite the monumental effect they have had on the world, vaccines are not without controversy, especially in recent years. They have been brought up in political spheres and in the media, with scientists, doctors, and others debating their ingredients and possible association with developmental disabilities.
In 1900, very few measures were in place to prevent infectious diseases such as smallpox, measles, diphtheria, and pertussis. Momentous strides have been made towards eradicating infectious diseases in America. Early forms of vaccines had been produced at the beginning of the 20th century, but none were widely distributed enough to have a widespread effect on the population. Since then, vaccinations have been developed for 21 diseases, 11 of which are recommended to be administered to all children in the US. The introduction of the polio vaccine by Jonas Salk and the allocation of federal funds for it brought vaccines to the forefront of healthcare providers’ minds. Polio and smallpox are now considered eliminated in the US, and vaccination rates have reached record highs, despite growing controversies. More recently, an Ebola vaccine was shown to have a 100% protection rate against the virus, a West African epidemic from 2014-2016.
Vaccine policies for children vary by state. Only 33 states and Washington D.C. require vaccinations, with exceptions for religious and medical reasons. The other 17 states do not require them on the grounds of moral or philosophical reasons. All but three states accept religious objection as a reason to not vaccinate, and all 50 states accept medical exemptions. California, Mississippi, and West Virginia do not accept any reason except a medical one as a reason to not vaccinate.
The debate over vaccinations and their possible dangers began in earnest when Andrew Wakefield, a former British doctor, published an unethical and unrepresentative study in 1998 purporting to show a link between the measles, mumps, and rubella vaccination (MMR) and autism spectrum disorder (ASD), a developmental disability that affects 1 in 68 children in the US. He hypothesized that the MMR vaccine would cause intestinal inflammation, leading to harmful proteins entering the brain, which would in turn cause the child to develop autism. His faulty study has since been disproved, with numerous studies showing no correlation between the MMR vaccine and ASD. Not only was his sample tiny (only 12 children with developmental delays were studied), but his assertion that vaccines could cause damage reaching the brain was completely false. One discrepancy was that 90% of children in England at the time received the MMR vaccine, and it was administered usually around the same time in a child’s life that they are diagnosed with autism. It should not be surprising, therefore, for some of the children vaccinated (as almost all children were) to develop a fairly common disorder. He would have needed to study both vaccinated and unvaccinated children to establish a connection between the MMR vaccine and ASD. The faulty logic that has tricked so many parents is post hoc, ergo propter hoc; correlation does not imply causation.
Wakefield published a second study, examining the relationship he “established” in the first, in 2002. He tested intestinal biopsy samples of children with and without autism for measles, and the results showed that 75 out of 91 of children with autism had the virus, compared to only 5 out of of 90 without autism. However, this study was equally as flawed. There was no mention of experimental blinding, in which the experimenter does not know who they are testing (in this case, an autistic or non-autistic child). This can be an essential step in an experiment, especially when a scientist is trying to prove a point. The experimenters also did not distinguish between vaccine virus and natural measles virus. Their method of collecting the data was also very prone to producing false positives. Despite the first article being retracted by The Lancet, the British medical journal that initially published Wakefield’s findings, and Wakefield’s medical license being revoked, many people around the world still believe that vaccines are somehow directly related to ASD.
Some parents are certain that because some children developed a relatively common neurological disorder after being inoculated that the vaccine must have caused the disorder. This is the misconception that continues to affect America’s public health. Despite the original study being discredited and many subsequent ones showing the opposite conclusion, many still have faith in Wakefield’s original assertion. This has lead to a chain reaction, culminating in several outbreaks of measles since the publication of the study.
A parent reads about and believes the faulty study, and the parent decides to withhold vaccination from their child(ren). The child then gets sick and infects others. One instance of this was the 2008 San Diego outbreak, in which an unvaccinated boy brought the measles virus back from a family trip to Europe. The boy infected an additional 11 children, some from his school and pediatrician’s office. 36 of the 376 children who attended his school were unvaccinated due to personal beliefs, which was allowed under California law at the time. This was changed by California’s Senate Bill 277 , which was signed on June 30, 2016. California no longer allows religious or philosophical vaccine exemptions. The bill caused controversy among Californians, some of whom began looking for homes in states without a similar law.
The issue was brought into the spotlight again in 2014 when a measles outbreak occurred at Disneyland, which re-sparked a national debate over vaccinations. The case lead to 125 cases of measles, 110 of which resided in California. Of these 110 individuals, 45% were unvaccinated, and 43% had an unknown or undocumented vaccination status. Of the 49 unvaccinated people, 12 were too young to be vaccinated. Of the 37 who were eligible to be vaccinated, 28 were intentionally unvaccinated, citing personal beliefs. The presence of unvaccinated individuals and the fact that the measles virus can linger in the air for two hours following a single sneeze makes for a dangerous combination. Measles is incredibly contagious because an infected person is contagious for four days before and four days after developing the rash. Several other measles outbreaks, each varying in size, have happened across the US, many stemming from unvaccinated individuals returning home from Europe and the Philippines.
Other factors besides the lingering damage of Wakefield’s article have affected people’s view on vaccines. Some believe that parents’ lack of worry for their child’s safety stems from not being exposed to the disease themselves. In reference to polio, a debilitating disease effectively eliminated by the vaccine, Seth Mnookin, author of The Panic Virus, remarked, “you might as well be protecting against aliens — these are things they’ve never seen.” The lack of exposure to the effects of the disease leaves Americans without the fear their parents and grandparents had of the disease. Mnookin also cites doctors’ absence of absolute language in their conclusions, increasing doubt. The anti-vaccine movement has also been supported by various celebrities, including actress Jenny McCarthy. Oprah Winfrey backed McCarthy up, saying, “she knows what she’s talking about.” Actor Jim Carrey (who was dating McCarthy for a time) also tweeted his disapproval of vaccine ingredient Thimerosal. Many blogs and other sites have popped up, some claiming their pediatricians blamed their child’s autism on vaccines and others pointing out “corruptions” of the CDC (Centers for Disease Control). Each of these factors has lead to a rise in anti-vaccine sentiment.
Vaccines have also made an appearance in the political sphere. The late 2014 outbreak caused tension in the G.O.P. Early hopefuls for the 2016 Presidential election had to take a stance on the issue. Governor Chris Christie of New Jersey was quoted saying, “parents need to have some measure of choice” in whether or not to vaccinate their children. He later modified his stance, saying there is “no question” children should be vaccinated. Rand Paul, Carly Fiorina, and Rick Perry all voiced their support for some measure of parents’ choice in the matter. Other prominent Republicans, such as Marco Rubio and Bobby Jindal, maintained that all children should be vaccinated.
There has been disagreement over how to change the mind of “anti-vaxxers.” A 2014 experiment conducted by Brendan Nyhan, Jason Reifler, Sean Richey, and Gary L. Freed, titled, “Effective Messages in Vaccine Promotion: A Randomized Trial” tested four methods of promoting vaccines to parents of young children. Methods included explaining the harmful effects of the diseases the MMR vaccine prevents, images of children affected by these diseases, research on the absence of correlation between the MMR vaccine and autism by the CDC, and a story of an infant dying from an MMR vaccine prevented illness. While the method of delegitimizing MMR correlation to autism “successfully reduced misperceptions that vaccines cause autism,” the method had the opposite effect on likeliness to vaccinate than the researchers had hoped for. The other methods produced similar results—none increased a parents’ likelihood of vaccinating their child(ren).
However, a different study lead by Zachary Horne (this one including both parents and non-parents) the next year showed different results. One group (similar to one in the previous study) was given a narrative written in a motherly tone about her child with measles, as well as photos of children with MMR prevented diseases and warnings against refusal of vaccination. Another group was given reading material showing no correlation between autism and the MMR vaccine, while the third was a control. Both the control group and the group given the material showing that the MMR vaccine does not cause autism showed a small increase in approval of vaccines. Strikingly, the other group given the story, photos, and warning had an increase in approval five times that of the increase for the group receiving the research. Dr. Kathryn C. Zoon, former Director of the Center For Biologics Evaluation and Research at the FDA (Food and Drug Administration) and former Director of the Division of Intramural Research at NIH (National Institutes of Health), believes the best way to encourage skeptical parents to vaccinate their children is for researchers to “be transparent about the data collected on vaccine safety and effectiveness.” She adds that parents should “participate [in] web advisory board meetings of the FDA and CDC which discuss new vaccines and the vaccine schedules.”
Herd immunity, the idea that the more people that are vaccinated, the safer the unvaccinated people are, is the reason many are urging others to vaccinate. If no one in the community is vaccinated, than one sick person quickly infects a certain number of people, each of whom infect a certain number more, and soon enough the entire population is infected. Vaccinating some of the population reduces the risk of infection to unvaccinated people because there is a decreased number of potential contaminants. This reduction is called the herd effect. The herd immunity threshold is the number of people that can be affected by each sick person in order for an outbreak to end quickly. This number is (on average) less than one person. For every increase in the number of vaccinated people, the risk to people who cannot vaccinate for medical reasons (such as chemotherapy or a weakened immune system), or are too young to vaccinate, decreases. If the person is surrounded by people who are not sick, they are much less likely to be infected.
Thimerosal, an ingredient that used to be much more commonly used in vaccines, has also been a point of concern for parents. An amendment was added to the Food and Drug Administration Modernization Act in November 1997 that called for the eventual removal of Thimerosal from vaccines, with the exception of multi-dose preparations of the influenza vaccine. Since 2001, thimerosal has been removed (except for trace amounts in some cases) from routine vaccinations for children, except for some flu vaccines. It has been used to prevent bacterial growth since the 1930s, and is still used to ensure the sterility of the production line in the early stages of vaccine production as well as in nose and throat sprays. However, the vaccines are later purified and contain only 1% of the amount of Thimerosal in earlier vaccines.
Despite concern, it has been found that there is no link between Thimerosal and neurodevelopmental disorders, such as autism. Thimerosal is ethylmercury-based, but it is different from mercury found in the environment (methylmercury). Some were concerned that receiving a vaccine containing thimerosal would result in mercury poisoning and/or autism. The two types of mercury are processed differently in the body. Methylmercury can be toxic to people at high levels as it is exposed to bacteria that transforms it from inorganic mercury to organic mercury. Ethylmercury goes through the body ten times more quickly than methylmercury, making it much less likely to accumulate in the body than methylmercury. Another reassurance to parents is that more methylmercury is present in the environment (such as through water and infant formula) than one would ever be exposed to through a vaccine. Numerous studies have shown that the number of diagnoses of autism did not decrease following the removal of Thimerosal, and that it even increased, including by the American Journal of Preventive Medicine.
The most recent resurfacing of the vaccine debate involves Robert Kennedy, Jr., and President Donald Trump. Kennedy stated that he was asked by the President to lead a commission on “vaccine safety.” Kennedy is known for his disapproval of vaccines, specifically ones containing Thimerosal. He edited the 2014 book Thimerosal: Let the Science Speak. He maintains that thimerosal is a cause of neurological disorders.
Though vaccine policy, ingredients, and their place in politics can be endlessly debated, the science behind vaccines and their safety can’t. Vaccines do not cause autism (or any other developmental disability), or mercury poisoning, as shown by countless studies and thousands of sampled children. Despite the indisputable scientific evidence that vaccines are safe, the Wakefield study, which was published 19 years ago, continues to have an effect on public health in the United States.
All photos courtesy of NIH NIAID via Flickr.