By Gary Evans, Senior Writer
Infection preventionists should be vigilant for incoming measles cases, as some 9 million U.S. children — 1 in 8 of those age 17 and younger — are susceptible to a virus that can cause chaotic outbreaks in healthcare facilities, researchers recently reported in San Diego at IDWeek 2015.
If the trend continues to increase, millions of susceptible youth — and eventually young adults — could reach a tipping point in population herd immunity, meaning more frequent and sustained measles outbreaks could occur.
“We can’t be complacent — we don’t have a very wide buffer before these population-level immunity estimates start dipping below critical levels,” said lead researcher Robert Bednarczyk, PhD, a professor in the Rollins School of Public Health at Emory University in Atlanta. “If our measles immunization starts to falter we could see immunity below what we need to [prevent] transmission. We could start seeing larger outbreaks or outbreaks that sustain over longer periods of time.”
An undiagnosed case of measles in a hospital can set off a frantic investigation to determine exposures and ensure immune status among staff and patients. As we recently reported, a single case of pediatric measles set off a staggering and expensive series of events at a hospital that included hundreds of blood tests, furloughed workers, and patient notifications. (See Hospital Infection Control & Prevention, October 2015.) And, as IPs are well aware, there is an anti-vaccine movement in the U.S. that has cast suspicion on all immunizations and linked the MMR shot erroneously with autism.
Based on an analysis of national immunization survey data, the IDWeek study estimates that of 60 million U.S. children from infants to 17-year-olds, 8.7 million (12.5%) are susceptible to measles.1 This is primarily because they haven’t received the MMR vaccine, or they have received only one of the two recommended doses. (The first dose of MMR vaccine is recommended at 12 to 15 months of age and the second at four to six years old.) Of the total susceptible population, 6.7 million children are of an age recommended to be immunized for measles but have not been vaccinated. The remaining 2 million are under one year of age and thus not yet recommended for MMR, but it is important to include them because they are at greater risk of serious complications if they acquire measles, Bednarczyk said at an Oct. 8 IDWeek press conference.
School age spike
The data show a vaccination “bubble” or spike at around five years of age, suggesting school requirements have an impact, he said. However, many states allow exemptions for religious or personal reasons in addition to medical contraindications to the vaccine. Overall, the immunization rate trends upward with age, approaching the mid-90s in older teens who are more likely to have contact with more people. While that is generally good news, that still leaves one in four children three years and younger at risk of measles and even 5% of the 17-year-olds have not received any doses of the vaccine. Even if current immunization rates don’t further decline, there are pockets and clusters of vulnerable populations who can set off rapidly expanding measles outbreaks.
“As a pediatrician and a public health officer it is frustrating to admit children to hospitals for a disease that is very preventable and generally we felt was gone,” said Matthew Zahn, MD, of the Orange County (CA) Health Care Agency.
Participating in the IDWeek measles discussion, Zahn said his county had 35 cases of measles at the beginning of this year as part of a large national outbreak that began at Disneyland.
“It was sobering to recognize that one exposure can cause so many cases around the country,” he said. “We have a significant number of kids in this country who are [non- or] under-immunized and it is terribly important that providers emphasize immunization.”
Currently, outbreaks typically burn out when they reach adult populations more likely to be immunized or have a history of natural infection. However, that firewall of sorts is subject to change as the demographic of non-vaccinators ages.
“There is a creeping nature to the problem in the sense that vaccine hesitancy is really coming of age to some degree,” Zahn said. “We now see kids of 15 or 18 years of age whose parents have not vaccinated them because they have concerns about the safety of the vaccines.”
These vaccine concerns were inflamed by comments made at a recent Republican presidential debate seen by 23 million television viewers.
GOP debate fuels fears
Three GOP candidates — two of them physicians — made comments at the Sept. 16 debate that either gave new life to the old lie that vaccines are linked to autism or suggested that childhood shots are unsafe because too many are given at the same time. Here is part of the exchange that occurred at the debate.
Candidate Donald Trump said, “Autism has become an epidemic. Twenty-five years ago, 35 years ago, you look at the statistics, not even close. It has gotten totally out of control. I am totally in favor of vaccines. But I want smaller doses over a longer period of time. …You take this little beautiful baby, and you pump — I mean, it looks just like it’s meant for a horse, not for a child. We’ve had so many instances, people that work for me. Just the other day, two-and-a-half years old, a beautiful child went to have the vaccine, and came back, and a week later got a tremendous fever, got very, very sick, now is autistic.”
Candidate Ben Carson, MD, a pediatric neurosurgeon, rejected the autism-vaccine link. However, he took a conciliatory tone that some found far too tepid when the leading candidate had just made a statement that is patently false and potentially life-threatening by justifying parents who deny vaccines to their children. “The fact of the matter is we have extremely well-documented proof that there’s no autism associated with vaccinations,” Carson said. “But it is true that we are probably giving way too many [vaccines] in too short a period of time.”
Candidate Sen. Rand Paul, (R-KY), MD, an ophthalmologist, then added: “I’m all for vaccines. But I’m also for freedom. I’m also a little concerned about how they’re bunched up. My kids had all of their vaccines, and even if the science doesn’t say bunching them up is a problem, I ought to have the right to spread out my vaccines a little bit at the very least.”
There was immediate concern that the high-profile discussion will reinvigorate the anti-vaccine movement in the U.S. and give pause to healthcare workers who are being strongly urged to overcome historical resistance and receive all recommended vaccines.
‘Dangerous’ comments
The comments were roundly condemned by the medical community, with the American Academy of Pediatrics (AAP) calling them both false and dangerous. “Claims that vaccines are linked to autism, or are unsafe when administered according to the recommended schedule have been disproven by a robust body of medical literature. It is dangerous to public health to suggest otherwise,” the AAP said in a statement. “There is no ‘alternative’ immunization schedule. Delaying vaccines only leaves a child at risk of disease for a longer period of time; it does not make vaccinating safer.”
The physician candidates should have rebuked Trump more forcefully for the autism comments and only confused the issue more by endorsing the false notion that there is some risk to children due to the timing of the immunizations, says William Schaffner, MD, longtime vaccine advocate and professor of preventive medicine at Vanderbilt University School of Medicine in Nashville.
“First, there is no doubt that there is no connection between vaccines and autism. That’s number one and must be stated strongly,” he tells Hospital Infection Control & Prevention. “It is disheartening that two physicians were part of that debate and did not strongly make the point that vaccines are not associated with autism. Some of that was said, but it was not said with the explicitness and the force needed.”
Although his equivocal tone could have been more about politics than medicine, Carson did at least refute the autism link. However, he then doubled down, as did Paul, on the pediatric immunization schedule.
“The conversation slipped into the issue of stretching out the routine childhood immunization schedule and that’s where the train went completely off the rails,” Schaffner says. “Because those physicians offered commentary that seemed to support stretching out the immunization schedule, for which there is no good reason, no evidence, and it only keeps children susceptible to the diseases the vaccines are designed to prevent for longer periods of time.”
This contention was born out by an Institute of Medicine (IOM) report that concluded, “Upon reviewing stakeholder concerns and scientific literature regarding the entire childhood immunization schedule, the IOM committee finds no evidence that the schedule is unsafe. The committee’s review did not reveal an evidence base suggesting that the U.S. childhood immunization schedule is linked to autoimmune diseases, asthma, hypersensitivity, seizures, child developmental disorders, learning or developmental disorders, or attention deficit or disruptive disorders.”2
Similarly, an IOM report that reviewed more than 1,000 studies found no link between vaccines and autism.3 A study published this year in the Journal of the American Medical Association found no link between MMR vaccine and autism after looking at 95,000 children from birth to at least five years of age.4 There was no link even among children already at higher risk for autism due to an existing diagnosis in an older sibling.
“Study after study has concluded that there is no risk [or connection] between vaccines and autism,” said Tom Frieden, MD, director of the CDC. “There is, though, a very serious problem of autism. The discussion of vaccines and autism unfortunately has, at times, interfered with our ability to study further what is causing autism so we can both prevent it better and provide better services to the children and families who have autism.”
Frieden’s comments were made one day after the debate at a Sept. 17 influenza meeting and press conference held by the National Foundation for Infectious Diseases (NFID). The director made the point that the CDC is the agency collecting reports and documenting the increase in autism, leaving unasked the question of why would an agency try to “hide” or deny a link between vaccines and autism while simultaneously reporting an increase in the childhood disease. In terms of the scheduling of childhood shots, Frieden said that is discussed and set in open meetings by the CDC’s Advisory Committees on Immunization Practices (ACIP).
“[ACIP] works in a completely transparent fashion,” Frieden said. “All of the meetings, all the documents are open to the public. There are individuals and entities represented on ACIP from all sectors of society, including patient groups. And this is not just the most effective way of setting vaccine policy. It’s a model for countries around the world. Because let’s be frank — for most vaccines, there are some people who think that there’s something bad about them. And there is hardly a vaccination program that’s been run in any country, anywhere in the world, ever, that hasn’t had some rumors circulating about it. The best disinfectant for rumors is transparency.”
Shortly after the debate, the Autistic Self Advocacy Network issued a statement that said, “Politicians continue to talk about an autism epidemic — despite the fact that science suggests that autism has always existed at its current rate within the general population. Autistic people are not new — and neither are our unmet needs. Vaccinations do not cause autism — but the use of autism as a means of scaring parents from safeguarding their children from life-threatening illness demonstrates the depths of prejudice and fear that still surrounds our disability.”
The vaccine safety issue was originally seized on by some to explain the perceived dramatic increase in autism over the last few decades. The theory was aided and abetted by publication of a later-retracted study in Lancet that falsely suggested MMR vaccine administration triggered the onset of autism in children.5 However, it appears that much of this autism increase has been due to changing definitions — “diagnostic substitution” — that have increased the number of intellectual disabilities defined as autism. This surveillance artifact accounted for a 64% increase in autism diagnosis from 2000-2010, researchers recently concluded.6
However, critics have pointed out that diagnostic substitution does not explain all of the increase, and vaccine researcher Paul Offit, MD, of the Children’s Hospital of Philadelphia, has observed that the autism issue may cast a shadow over vaccine safety until the real reasons for the disorder are completely understood. Complicating matters, the CDC is expected to tighten the autism definition in the near future, winnowing out other intellectual disabilities that have heretofore fallen under the broad category. A more restricted clinical definition will likely lower the number of reported autism cases. If this occurs, we could see another round of controversy as critics accuse the CDC of manipulating the data.
REFERENCES
- Bednarczyk R, Orenstein WA, Omer, S. Poster 1866. Estimating the Number of Measles-susceptible Children in the United States Using the NIS-Teen. Poster 1866. IDWeek Oct. 7-11 2015. San Diego, CA.
- Institute of Medicine. The Childhood Immunization Schedule and Safety: Stakeholder Concerns, Scientific Evidence, and Future Studies. Report Brief. Jan. 16, 2013: http://bit.ly/1M0aN1V.
- IOM. Adverse Effects of Vaccines: Evidence and Causality. August 25, 2011:http://bit.ly/1YnWZrn.
- Jain A, Marshall J, Buikema A, et al. Autism Occurrence by MMR Vaccine Status Among US Children With Older Siblings With and Without Autism. JAMA 2015;313(15):1534-1540.
- Editors of The Lancet: Retraction—Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children. Lancet 2010;375:445.
- Polyak A, Kubina RM, Girirajan S. Comorbidity of intellectual disability confounds ascertainment of autism: implications for genetic diagnosis. Am J Med Genet B Neuropsychiatr Genet 2015;168(7):600-608.
Infection preventionists should be vigilant for incoming measles cases, as some 9 million U.S. children — 1 in 8 of those age 17 and younger — are susceptible to a virus that can cause chaotic outbreaks in healthcare facilities, researchers recently reported in San Diego at IDWeek 2015.
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