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IDCM CME Issue 1-9: Measles Outbreaks in the United States and Vaccine Refusal
Natasha Chida, MD, MSPH
What is measles?
Measles is a highly contagious viral disease. Following exposure, 90% of persons without immunity to the virus will develop measles.1 Prior to widespread measles vaccination, 2 million people died annually from the disease worldwide.2 Currently it is estimated measles kills 100,000 people annually. Unfortunately,in recent years a 30% increase in measles cases have occurred globally.3
How does measles present?
Measles typically begins with several days of fever and malaise, followed by and then conjunctivitis, cough, and nasal congestion. This is usually followed by a rash that begins on the face and spreads to cover the body. Most people recover following resolution of the rash; however, complications occur in up to 30% of persons, and include diarrhea, keratoconjunctivitis (which can cause blindness), pneumonia, bronchiolitis, encephalitis, acute disseminated encephalomyelitis (a demyelinating syndrome that can affect the brain and spinal cord), and subacute sclerosing pancencephalitis (which is generally fatal).2,4 The majority of measles deaths are related to pulmonary complications.
How is measles treated?
No antiviral treatments are available for measles; therapy is supportive and includes vitamin A administration, which can reduce morbidity and mortality.2 Given the lack of treatment for measles, the best way to reduce death and disability is through mass vaccination. Due to its high infectivity, levels of measles immunity in communities need to be as high as 89-94% to achieve measles elimination.2
What is the state of measles in the United States?
The measles vaccine became available in 1963; prior to that, 3-4 million people contracted the disease each year. Of these, 400-500 people died, 1,000 developed encephalitis, and 48,000 were hospitalized.5 Fortunately, following national MMR vaccination (measles, mumps, and rubella vaccine) campaigns, measles was eliminated in the United States in 2000; however, this does not mean measles cases do not occur. Elimination means absence of continuous disease for more than 12 months; that is, while measles is not endemic in the United States, measles cases occur during specific outbreaks.
In 2016, the overall national coverage for MMR vaccine among children aged 19–35 months was 91.1%.5 However, MMR vaccine coverage levels vary by state, and coverage in several states and local areas is below 90%. This is concerning, as a 5% decline in MMR vaccination in the United States is estimated to result in a 3-fold increase in cases annually among children, and an additional 2.1 million in public sector costs.6
Pockets of lower vaccination coverage have allowed for outbreaks of measles to occur in the last decade. In 2018 there were 372 cases of measles in the United States, and in 2019 so far 127 cases have occurred.5 These cases have presented primarily in persons who were intentionally not vaccinated, but also in persons who cannot get vaccinated because they either are too young or have an immune compromising condition.
Measles in the United States in 2019
An outbreak of measles is defined as 3 or more cases. Currently there are 5 outbreaks occurring in the United States; 3 are in New York State, 1 is in Washington, and 1 is in Texas.5 Each of these outbreaks appears to be linked to travelers bringing measles into the United States with subsequent spread among under- and unvaccinated individuals.5 The largest outbreak is in Washington, where 64 cases have been confirmed.7
The World Health Organization has declared vaccine hesitancy as one of the 10 threats to global health in 2019.3 On an individual level, studies have shown the following factors are causes of vaccine hesitancy: the perception that vaccines are not effective or useful; concerns about safety and side effects; distrust of the health system; a preference for “natural health;” fear of pain and needles; lack of awareness; and prior negative experiences with vaccines.8 On a community level, vaccine hesitancy is seen across educational and socioeconomic backgrounds. Misinformation about vaccines spread on social media also has been a driver of vaccine hesitancy in recent years, as has negative media coverage of vaccines, including coverage of celebrities who promote vaccine refusal.8
Requirements around childhood vaccination vary by state, and can be lax. In a review of vaccine preventable diseases in the United States, 18 studies were identified that in total described 1416 measles cases. Of these, vaccination data was available for 970 cases; 70.6% of these had nonmedical exemptions to vaccination (eg, exemptions for religious or philosophical reasons).9
How did modern vaccine hesitancy around the MMR vaccine begin?
In 1998 a British gastroenterologist named Andrew Wakefield published a paper in the prestigious journal Lancet detailing 12 cases of children who received MMR vaccination and then developed symptoms of regressive autism within the month.10 Dr. Wakefield reported that all of the children had gastrointestinal symptoms and evidence of colonic inflammation on endoscopy, and postulated that MMR had caused intestinal inflammation that lead to peptides in the GI tract translocating to the bloodstream, traveling to the brain, and causing autism. There were many methodologic issues with the study, which were noted soon after it was published. There were no controls, the cohort was self-referred, and there was no way to differentiate between coincidence and causality, given the small number of cases. The timing of MMR vaccination also occurs between ages 1-2, when signs of autism begin to manifest. There was no blinding of the endoscopic or neuropsychological assessments, and the gastrointestinal symptoms didn’t predate an autism diagnosis in many of the children.
Despite these issues, the article was widely publicized and vaccination rates in Britain began to decrease.11 Then, in 2004, an investigative journalist uncovered evidence of research fraud, conflicts of interest, and unethical treatment of children in the study. This led to the General Medical Council, the official register of physicians in the United Kingdom, to investigate the authors of the study. The journalist in the meantime continued to investigate the origins of the paper. In 2010 the paper was fully retracted based on the following information that was uncovered over the course of a decade:11-12
- The study was funded by a lawyer representing parents in a lawsuit against vaccine companies; this had not been disclosed.
- The same lawyer paid Dr. Wakefield $230 an hour; in total Dr. Wakefield had had earned an undisclosed $435,643.
- While conducting his study, Dr. Wakefield had planned to launch a diagnostics, immunotherapeutics, and vaccine company. The company was planned based on results of the study, which hadn’t been completed or published yet.
- The children were subjected to invasive procedures later found to be clinically unwarranted.
Data about some of the children in the study had been distorted, including:
- The onset of their symptoms with relation to receiving MMR vaccine
- The presence of developmental delays preexisting vaccination
- Recruitment--some of the children’s parents were clients of the same lawyer
- Colonic pathologic findings of the biopsies done during the study had been changed
- Of the 9 cases reported to have regressive autism in the paper, 3 did not have autism, and only one child had regressive autism
While the paper has been retracted, the effects of it continue to manifest in concerns about vaccines and autism. Numerous well-done and large-scale studies (some examining millions of children) have followed the 1998 Wakefield paper, and none have found a link between MMR and autism.10 Dr. Wakefield lost his British medical license and now lives in the United States, where he is vocal against vaccination.
In 2017, a Somali community in Minnesota experienced a measles outbreak. 65 confirmed cases occurred.14 MMR vaccination rates in this community had dropped from 92% in 2004 to 42% in 2014 due to fears of high rates of autism in the community. These fears lead antivaccine advocates to interface with the community; Dr. Wakefield had lectured to members in 2010-2011, when vaccine rates were falling. A study by the University of Minnesota found no difference in the rates of autism among children from the Somali community in Minnesota and white children.
Bottom line: Measles outbreaks in the United States are occurring annually, and are preventable by achieving high community levels of MMR vaccination. There is no link between MMR vaccination and autism.
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- Centers for Disease Control and Prevention. Transmission of Measles web page. https://www.cdc.gov/measles/about/transmission.html. Accessed 2/20/2019.
- Moss WJ. Measles. Lancet. 2017 Dec 2;390(10111):2490-2502.
- World Health Organization. Ten threats to global health in 2019. https://www.who.int/emergencies/ten-threats-to-global-health-in-2019. Accessed 2/19/19.
- Atkinson W, Wolfe C, Hamborsky J (Eds). Epidemiology and Prevention of Vaccine-Preventable Diseases (The Pink Book), 12th ed. The Public Health Foundation, Washington, DC 2011.
- Centers for Disease Control and Prevention. 2019. Measles. https://www.cdc.gov/measles/index.html. Accessed 2/20/2019.
- Lo NC, Hotez PJ. Public Health and Economic Consequences of Vaccine Hesitancy for Measles in the United States. JAMA Pediatr. 2017 Sep 1;171(9):887-892.
- Washington State Department of Health. 2019. Measles Outbreak 2019. https://www.doh.wa.gov/YouandYourFamily/IllnessandDisease/Measles/MeaslesOutbreak. Accessed 2/19/20.
- Dube E and MacDonald NE. Vaccine Hesitancy. Global Public Health. 2018. http://oxfordre.com/publichealth/view/10.1093/acrefore/9780190632366.001.0001/acrefore-9780190632366-e-63. Accessed 2/20/2019.
- Phadke VK, Bednarczyk RA, Salmon DA, Omer SB. Association Between Vaccine Refusal and Vaccine-Preventable Diseases in the United States: A Review of Measles and Pertussis. JAMA. 2016 Mar 15;315(11):1149-58.
- Gerber JS, Offit PA. Vaccines and autism: a tale of shifting hypotheses. Clin Infect Dis. 2009 Feb 15;48(4):456-61.
- Deer B. How the case against MMR was fixed. BMJ. 2011 Jan 5;342:c5347
- Deer, B. How the Vaccine Crisis was meant to make money. BMJ. 2011 Jan 11;342:c5258.
Dyer O. Measles outbreak in Somali American community follows anti-vaccine talks. BMJ 2017;357:j2378.