Controversy over the measles vaccine, and the spate of vaccine noncompliance that underlies the current measles outbreak in the United States, stem mostly from a totally debunked 1998 study by former British surgeon, Andrew Wakefield. In Wakefield’s now infamous report, he and co-authors claimed to find a link between the measles vaccine and autism. Here are some essential facts concerning measles, the measles vaccine, and Wakefield’s paper.
We begin with the crucial concept of herd immunity. People who cannot get vaccinated (e.g., young infants, pregnant women, children suffering from leukemia or other immune deficiencies) are nonetheless protected from measles by herd immunity; the immunity in the whole population that results when a high enough percentage of individuals in the population has been vaccinated. When herd immunity is attained, there are not enough susceptible individuals in the population to sustain the chain of transmission.
But, if enough parents opt out of having their children vaccinated, then herd immunity is lost, and outbreaks might then occur, as is happening now. Herd immunity against measles requires vaccination rates as high as 95 percent. That is so because measles is one of the most contagious of all viruses. Yet, all too many parents are now opting out of vaccinating their children; in many cases for fear that the measles vaccine might cause autism.
The measles incubation period is another important issue. The elapsed time, between initial infection and onset of illness, averages 10–12 days (rash may not appear until 18 days). Moreover, infected individuals can transmit the virus for several days before becoming ill. These points, together with the exceptionally high rate of measles transmission, mean that keeping sick children home from school or play group, is not an effective means for containing spread of the disease.
Next, consider the severity of measles, which all too many people, including some medical professionals, do not appreciate. [I heard one medical doctor on TV say measles is like the common cold.] Before the introduction of the first measles vaccine in 1963, and the WHO-sponsored global eradication program, death rates from measles ran as high as 7 to 8 million children, worldwide, annually. And, despite the current availability of effective measles vaccines, there still are more than 30 million measles cases per year worldwide, of which more than 1 million are fatal. As you might expect, the vast majority of fatal measles cases occur in unvaccinated populations in the developing world. In fact, in some unprotected groups, measles is the major cause of death in children less than five-years-old. [Reliable information on all aspects of measles can be found on line at “Measles – Centers for Disease Control and Prevention,” http://www.cdc.gov/…/meas.]
The above data unmistakably support the case for vaccination against measles. Ever since the first measles vaccine was introduced in 1963, the incidence of measles has been dramatically reduced in all regions of the world where vaccination programs were put in place. In the United States, the number of measles cases declined from about 500,000 per year before 1963, to no endemic cases whatsoever in 2000!
But, since measles persisted elsewhere in the world, and, since the measles virus is so highly contagious, it returned to the United States in the years between 1989 and 1991, when vaccination rates fell below the critical level needed to maintain herd immunity. In that earlier 1989 outbreak, poor compliance with vaccine programs was, ironically, due to the success of the vaccine program. Because measles was no longer existent in the United States, it was not in the public’s consciousness, resulting in public complacency towards vaccination.
At present, segments of the public are opting out of vaccinating their children largely because of Wakefield’s discredited 1998 paper in The Lancet, which asserted that the trivalent measles, mumps, and rubella (MMR) vaccine might cause autism. Here is the story of how and why Wakefield’s 1998 paper fell into disrepute.
The validity of Wakefield’s 1998 findings first came under question in 2004 when an article in the Sunday Times of London reported that Wakefield had not disclosed a conflict of interest that might have compromised his objectivity. The newspaper revealed that Wakefield accepted £55,000 ($103,000) to support his study, from lawyers representing parents of autistic children. The purpose of the financial support was to validate the parents’ legal claims against the vaccine manufacturer. Astonishingly, some of the families in Wakefield’s study actually were selected by these lawyers. Next, in 2006, the Sunday Times reported that the lawyers had paid Wakefield personally more than £400,000, none of which was ever reported.
Irrespective of Wakefield’s conflict of interest, the 1998 study was exceptionally weak on several counts. First, its conclusions were based on a sample size of only twelve children. What’s more (and virtually unbelievably), the association between the vaccine and autism was concluded merely from interviewing the children’s parents; people who were not likely to be the most objective of observers, since at least some were looking for someone or something to blame for their children’s condition.
The credibility of Wakefield’s already weak paper took a major hit when it was revealed in 2009 that he had manipulated patients’ data. Wakefield’s paper claimed that the families of eight of the twelve children attributed their children’s autism to the MMR vaccine and that the children’s problems emerged within days after their vaccinations. The Wakefield paper also reported the discovery of a new inflammatory bowel disease it associated with the vaccine, and it proposed that the new disease also might be connected to autism. However, an investigation by the British Medical Council (BMC) found that in most cases the data in The Lancet was not in accord with the children’s medical records. In only one case was there any suggestion that there was any problem within days of the vaccination. In fact, in many of the cases, the parents expressed concerns about autism before their children’s’ vaccinations. And, a November 2011 paper in the British Medical Journal reported that an investigation of Wakefield’s raw data revealed that none of the twelve children in his study had signs of inflammatory bowel disease.
The BMC’s investigating panel ruled that Wakefield had “failed in his duties as a responsible consultant”, acted both against the interests of his patients, and “dishonestly and irresponsibly” in his published research. What’s more, the British Medical Journal took the extraordinary step of publishing a report in which it concluded that Wakefield’s study was not simply bad science, but a deliberate and elaborate fraud. Shortly afterwards, Wakefield was removed from the United Kingdom’s Medical Register and barred from practicing medicine in the UK.
In a large scale study, involving more than a half million children, the U.S. Institute of Medicine (IOM), a respected independent arbiter, found no evidence whatsoever of any connection between vaccines and autism. Other large and well designed studies likewise found no such connection.
In 2010, The Lancet responded to the above revelations by retracting Wakefield’s 1998 paper. Moreover, ten of Wakefield’s twelve co-authors issued a retraction, which included the following: “We wish to make it clear that in this paper no causal link was established between (the) vaccine and autism, as the data were insufficient. However the possibility of such a link was raised and consequent events have had major implications for public health. In view of this, we consider now is the appropriate time that we should together formally retract the interpretation placed upon these findings in the paper…”
Despite these developments, Wakefield has stood by his claims, and many still regard him as a hero. What’s more, Wakefield’s claims continue to influence many parents, and they are a major reason for the sharp decline in vaccination rates in the United Kingdom and in the United States.
Why might The Lancet have published Wakefield’s 1998 paper in the first place? As explained by Richard Horton, Editor-in-Chief of The Lancet, the journal was interested in the new gastrointestinal disorder described in the paper, rather than in the parents’ testimony regarding a possible link between the MMR vaccine and autism. Horton states: “The central thrust of the paper was this new syndrome. This is not an uncommon kind of report. If you read any text book of epidemiology, the very first description of any new syndrome often comes with either a case report or a case series.” [Note the rather inconspicuous title of Wakefield’s highly flawed but influential paper: “Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children”]
Horton also noted that the journal was well aware that the Wakefield paper might have an adverse public health impact, which it sought to avoid by including in the paper the disclaimer that there was no proof of causation or association between the MMR vaccine and autism, and also by identifying the paper as an “early” report. But the media and the public could hardly be expected to disregard the sensational story behind the disclaimers.
We conclude with a few related items.
Doubts about Wakefield’s scientific credibility might have been raised before he ever turned his attention to the measles vaccine and autism. In 1993 he published reports concluding that the measles virus might cause Crohn’s disease, and two years after that he published a paper (in The Lancet) suggesting a link between the measles vaccine and Crohn’s disease. Neither of these claims could be verified by a number of subsequent peer-reviewed studies.
Some individuals believe that thimerosal (a mercury compound once added to some vaccines as a preservative) is the link between vaccines and autism. Regarding the possibility that thimerosal in the MMR vaccine might be responsible for autism, the MMR vaccine is a live vaccine, and thimerosol was added only to killed vaccines (e.g., the vaccines against diphtheria, whooping cough, and tetanus). What’s more, all routine vaccinations in the United States have been thimerosol-free since 2001.
One might presume that the way to convince vaccine skeptics of the safety of vaccines, and of their importance for the good of all, is for public health experts and medical practitioners to confront the deniers with the data and the facts. Yet the result of those efforts is usually quite the opposite of what is intended. When confronted with the facts, the deniers dig their heels in even deeper to hold on to their anti-vaccine position. And, we scientists don’t reassure the public by always qualifying our pronouncements with statements such as “to the best of our knowledge” or “as far as we know.” [I am by no means suggesting that we ought to abandon our inclination to not speak in absolutes.]
The state of affairs was not helped when some 2016 presidential aspirants (one of whom is a medical doctor) not only equivocated over the pubic health aspects of the vaccine controversy, but also framed it as an issue of government infringement on the peoples’ liberties. As expected, the latter position has more political potency among conservative voters. However, the debate does not break cleanly between liberals and conservatives, or along income or education demographics. In fact, the movement to forgo vaccinations has become popular in some more liberal and affluent communities; the organic grocery demographic. [Somehow it is better to expose a child to a dangerous disease, so that the child might have “natural” immunity to the disease, rather than have the child receive a safe vaccine that prevents the dangerous disease in the first place.] Even veterinarians are running up against the anti-vaccine movement, as more and more pet owners are foregoing vaccines against distemper and other pet ailments.
Because government enforcement of vaccine regimens might be viewed by many as an intrusion on individual liberty, all but two states (Mississippi and West Virginia) allow exemptions based on religious beliefs. In addition, nineteen states allow exemptions based on personal (whatever that may mean) beliefs. All states do allow medical exemptions, since some children (e.g. those receiving chemotherapy or who have certain immune disorders) cannot receive vaccines. Nevertheless, despite the fact that states in which it is easier to obtain non-medical exemptions have higher rates of vaccine-preventable disease, moves are afoot in several states (including Mississippi and West Virginia) to make it easier still to obtain personal belief exemptions.
Reference: Wakefield, A. J., S. H. Murch, A. Anthony, J. Linnell, D. M. Casson, M. Malik, M. Berelowitz, A. P. Dhillon, M. A. Thomson, P. Harvey, A. Valentine, S. E. Davies, and J. A. Walker-Smith. 1998. Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children. The Lancet 351:637–641.