A vaccine controversy is a dispute over the morality, ethics, effectiveness, or safety of vaccinations. Medical and scientific evidence surrounding vaccinations generally demonstrate that the benefits of preventing suffering and death from infectious diseases outweigh rare adverse effects of immunization.[1][2] However, since vaccination began in the late 18th century, opponents have claimed that vaccines do not work, that they are or may be dangerous, that individuals should rely on personal hygiene instead, or that mandatory vaccinations violate individual rights or religious principles.[3] These arguments have succeeded in reducing vaccination rates in certain communities, leading to increased outbreaks of preventable, and sometimes fatal, childhood illnesses.[4]
Vaccines may cause side effects, and the success of immunization programs depends on public confidence in their safety. Concerns about immunization safety often follow a pattern: some investigators suggest that a medical condition is an adverse effect of vaccination; a premature announcement is made of the alleged adverse effect; the initial study is not reproduced by other groups; and finally, it takes several years to regain public confidence in the vaccine.[1]
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One of the first documented "ideas" of vaccinations was in 1721 when Reverend Cotton Mather introduced inoculation to Boston, Massachusetts during the 1721 smallpox epidemic.[5] Most had religious objections to variolation, but Mather was able to convince Dr. Zabdiel Boylston to experiment with inoculation. Boylston first experimented on his 6-year-old son, his slave, and his slave's son; each subject contracted the disease and was sick for several days, until the sickness vanished and they were "no longer gravely ill".[5] Boylston went on to vaccinate thousands of Massachusetts residents with the result being many places named for him in gratitude.
Religious arguments against inoculation were advanced even before the work of Edward Jenner; for example, in a 1722 sermon entitled "The Dangerous and Sinful Practice of Inoculation" the English theologian Rev. Edmund Massey argued that diseases are sent by God to punish sin and that any attempt to prevent smallpox via inoculation is a "diabolical operation".[6] Some anti-vaccinationists still base their stance against vaccination with reference to their religious beliefs.[7]
After Jenner's work, vaccination became widespread in the United Kingdom in the early 19th century.[8] Variolation, which had preceded vaccination, was banned in 1840 because of its greater risks. Public policy and successive Vaccination Acts first encouraged vaccination and then made it mandatory for all infants in 1853, with the highest penalty for refusal being a prison sentence. This was a significant change in the relationship between the British state and its citizens, and there was a public backlash. After an 1867 law extended the requirement age to 14 years, its opponents focused concern on infringement of individual freedom, and eventually an 1898 law allowed for conscientious objection to compulsory vaccination.[3]
In the 19th century, the city of Leicester in the UK achieved a high level of isolation of smallpox cases and great reduction in spread compared to other areas. The mainstay of Leicester's approach to conquering smallpox was to decline vaccination and put their public funds into sanitary improvements.[9] Bigg's account of the public health procedures in Leicester, presented as evidence to the Royal Commission, refers to erysipelas, an infection of the superficial tissues which was a complication of any surgical procedure.
In the US, President Thomas Jefferson took a close interest in vaccination, alongside Dr. Waterhouse, chief physician at Boston. Jefferson encouraged the development of ways to transport vaccine material through the Southern states, which included measures to avoid damage by heat, a leading cause of ineffective batches. Smallpox outbreaks were contained by the latter half of the 19th century, a development widely attributed to vaccination of a large portion of the population. Vaccination rates fell after this decline in smallpox cases, and the disease again became epidemic in late 19th century (see Smallpox).[10]
Anti-vaccination activity increased again in the US in the late 19th century. After a visit to New York in 1879 by William Tebb, a prominent British anti-vaccinationist, the Anti-Vaccination Society of America was founded. The New England Anti-Compulsory Vaccination League was formed in 1882, and the Anti-Vaccination League of New York City in 1885.
John Pitcairn, the wealthy founder of the Pittsburgh Plate Glass Company (now PPG Industries) emerged as a major financier and leader of the American anti-vaccination movement. On March 5, 1907, in Harrisburg, Pennsylvania, he delivered an address to the Committee on Public Health and Sanitation of the Pennsylvania General Assembly criticizing vaccination.[11] He later sponsored the National Anti-Vaccination Conference, which, held in Philadelphia on October, 1908, led to the creation of The Anti-Vaccination League of America. When the League was organized later that month, Pitcairn was chosen to be its first president.[12] On December 1, 1911, he was appointed by Pennsylvania Governor John K. Tener to the Pennsylvania State Vaccination Commission, and subsequently authored a detailed report strongly opposing the Commission's conclusions.[12] He continued to be a staunch opponent of vaccination until his death in 1916.
In November 1904, in response to years of inadequate sanitation and disease, followed by a poorly explained public health campaign led by the renowned Brazilian public health official Oswaldo Cruz, citizens and military cadets in Rio de Janeiro arose in a Revolta da Vacina or Vaccine Revolt. Riots broke out on the day a vaccination law took effect; vaccination symbolized the most feared and most tangible aspect of a public health plan that included other features such as urban renewal that many had opposed for years.[13]
In the early 19th century, the anti-vaccination movement drew members from across a wide range of society; more recently, it has been reduced to a predominantly middle-class phenomenon.[14] Arguments against vaccines in the 21st century are often similar to those of 19th-century anti-vaccinationists.[3]
20th century events include the 1982 broadcast of "DPT: Vaccine Roulette" sparking debate over the DPT vaccine,[15] and the 1998 publication of an academic article (later discredited) which sparked the MMR vaccine controversy.
Mass vaccination helped eradicate smallpox, which once killed as many as one in seven children in Europe.[16] Vaccination has almost eradicated polio.[17] As a more modest example, incidence of invasive disease with Haemophilus influenzae, a major cause of bacterial meningitis and other serious disease in children, has decreased by over 99% in the US since the introduction of a vaccine in 1988.[18] Fully vaccinating all US children born in a given year from birth to adolescence saves an estimated 33,000 lives and prevents an estimated 14 million infections.[19] Some vaccine critics claim that there have never been any public health benefits from vaccination.[20][21] These critics argue that reductions in communicable disease prevalence, morbidity and mortality attributed to vaccines are actually the result of several other factors:
Intertwined with these factors is the assertion that many vaccine-preventable diseases were actually in decline prior to the introduction of vaccination.[21] The general medical consensus, however, is that such claims are misconceptions meant to imply that vaccination is unnecessary.[22]
Other critics argue that immunity given by vaccines is only temporary and requires boosters, whereas those who survive the disease become permanently immune.[3] As discussed below, the philosophies of some alternative medicine practitioners are incompatible with the idea that vaccines are effective.[23]
Vaccination critics argue that for diseases like diphtheria the extra risk to older or weaker adults may outweigh the benefit of lowering the mortality rate among the general population.[24]
Lack of complete vaccine coverage increases the risk of disease for the entire population, including those who have been vaccinated, because it reduces herd immunity. For example, measles vaccine targets children between the ages of 9 and 12 months, and the short window between the disappearance of maternal antibody (before which the vaccine often fails to seroconvert) and natural infection means that vaccinated children frequently are still vulnerable. Herd immunity lessens this vulnerability, if all the children are vaccinated. Increasing herd immunity during an outbreak or threatened outbreak is perhaps the most widely accepted justification for mass vaccination. Mass vaccination also helps to increase coverage rapidly, thus obtaining herd immunity, when a new vaccine is introduced.[25]
Commonly-used vaccines are a cost-effective and preventive way of promoting health, compared to the treatment of acute or chronic disease. In the US during the year 2001, routine childhood immunizations against seven diseases were estimated to save over $40 billion per birth-year cohort in overall social costs including $10 billion in direct health costs, and the societal benefit-cost ratio for these vaccinations was estimated to be 16.5.[26]
In several countries, reductions in the use of some vaccines were followed by increases in the diseases' morbidity and mortality.[27][28] According to the Centers for Disease Control and Prevention, continued high levels of vaccine coverage are necessary to prevent resurgence of diseases which have been nearly eliminated.[29]
An anti-vaccination campaign motivated by religious objections, by concerns about effectiveness, and by concerns about individual rights, led to the vaccination rate in Stockholm dropping to just over 40%, compared to about 90% elsewhere in Sweden. A major smallpox epidemic then started in 1873. It led to a rise in vaccine uptake and an end of the epidemic.[30]
In a 1974 report ascribing 36 reactions to whooping cough (pertussis) vaccine, a prominent public-health academic claimed that the vaccine was only marginally effective and questioned whether its benefits outweigh its risks, and extended television and press coverage caused a scare. Vaccine uptake in the UK decreased from 81% to 31% and pertussis epidemics followed, leading to deaths of some children. Mainstream medical opinion continued to support the effectiveness and safety of the vaccine; public confidence was restored after the publication of a national reassessment of vaccine efficacy. Vaccine uptake then increased to levels above 90% and disease incidence declined dramatically.[27]
In the vaccination moratorium period that occurred when Sweden suspended vaccination against whooping cough (pertussis) from 1979 to 1996, 60% of the country's children contracted the potentially fatal disease before the age of ten years; close medical monitoring kept the death rate from whooping cough at about one per year.[28] Pertussis continues to be a major health problem in developing countries, where mass vaccination is not practiced; the World Health Organization estimates it caused 294,000 deaths in 2002.[31]
An outbreak at a religious community and school in the Netherlands illustrates the effect of measles in an unvaccinated population.[32] The population in the several provinces affected had a high level of immunization with the exception of one of the religious denominations who traditionally do not accept vaccination. The three measles-related deaths and 68 hospitalizations that occurred among 2961 cases in the Netherlands demonstrate that measles can be severe and may result in death even in industrialized countries.
As a result of the MMR vaccine controversy vaccination compliance dropped sharply in the United Kingdom after 1996.[33] From late 1999 until the summer of 2000, there was a measles outbreak in North Dublin, Ireland. At the time, the national immunization level had fallen below 80%, and in part of North Dublin the level was around 60%. There were more than 100 hospital admissions from over 300 cases. Three children died and several more were gravely ill, some requiring mechanical ventilation to recover.[34]
In the early first decade of the 21st century, conservative religious leaders in northern Nigeria, suspicious of Western medicine, advised their followers not to have their children vaccinated with oral polio vaccine. The boycott was endorsed by the governor of Kano State, and immunization was suspended for several months. Subsequently, polio reappeared in a dozen formerly polio-free neighbors of Nigeria, and genetic tests showed the virus was the same one that originated in northern Nigeria: Nigeria had become a net exporter of polio virus to its African neighbors. People in the northern states were also reported to be wary of other vaccinations, and Nigeria reported over 20,000 measles cases and nearly 600 deaths from measles from January through March 2005.[35] In 2006 Nigeria accounted for over half of all new polio cases worldwide.[36] Outbreaks continued thereafter; for example, at least 200 children died in a late-2007 measles outbreak in Borno State.[37]
A 2005 measles outbreak in the US state of Indiana was attributed to parents who had refused to have their children vaccinated.[38] Most cases of pediatric tetanus in the US occur in children whose parents objected to their vaccination.[39]
Few deny the vast improvements vaccination has made to public health; a more common concern is their safety.[40] All vaccines may cause side effects, and immunization safety is a real concern. Unlike most other medical interventions, vaccines are given to healthy people, and people are far less willing to tolerate vaccines' adverse effects than adverse effects of other treatments. As the success of immunization programs increases and the incidence of disease decreases, public attention shifts away from the risks of disease to the risk of vaccination,[1] and it becomes challenging for health authorities to preserve public support for vaccination programs.[41]
Concerns about immunization safety often follow a pattern. First, some investigators suggest that a medical condition of increasing prevalence or unknown cause is an adverse effect of vaccination. The initial study, and subsequent studies by the same group, have inadequate methodology, typically a poorly controlled or uncontrolled case series. A premature announcement is made of the alleged adverse effect, resonating with individuals suffering the condition, and underestimating the potential harm to those whom the vaccine could protect. The initial study is not reproduced by other groups. Finally, it takes several years to regain public confidence in the vaccine.[1] Adverse effects ascribed to vaccines typically have an unknown origin, an increasing incidence, some biological plausibility, occurrences close to the time of vaccination, and dreaded outcomes.[42]
Controversies in this area revolve around the question of whether the risks of perceived adverse events following immunization outweigh the benefits of preventing adverse effects of common diseases. There is scientific evidence that in rare cases immunizations can cause adverse events, such as oral polio vaccine causing paralysis. Current scientific evidence does not support the hypothesis of causation for more-common disorders such as autism.[1][43] Although the hypotheses that vaccines cause autism are biologically implausible, it would be hard to study scientifically whether autism is less common in children who do not follow recommended vaccination schedules, because an experiment based on withholding vaccines from children would be unethical, and because results would likely be confounded by differences in health care seeking behaviors of under-vaccinated children.[44]
Vaccine overload is the notion that giving many vaccines at once may overwhelm or weaken a child's immature immune system and lead to adverse effects.[45] Although the scientific evidence strongly contradicts this idea,[44] some parents of autistic children firmly believe that vaccine overload causes autism. [46] The resulting controversy has caused many parents to delay or avoid immunizing their children.[45] Such parental misperceptions are major obstacles towards immunization of children.[47]
The idea of vaccine overload is flawed for several reasons.[44] Vaccines do not overwhelm the immune system; conservative estimates predict that the immune system can respond to thousands of viruses simultaneously.[44] Despite the increase in the number of vaccines over recent decades, improvements in vaccine design have reduced the immunologic load from vaccines, such that the total number of immunological components in the fourteen vaccines administered to US children in 2009 is less than 10% of what it was in the seven vaccines given in 1980.[44] Vaccines constitute only a tiny fraction of the pathogens naturally encountered by a child in a typical year[44] and common childhood conditions such as fevers and middle ear infections pose a much greater challenge to the immune system than vaccines do.[48] Second, studies have shown that vaccinations, and even multiple concurrent vaccinations, do not weaken the immune system[44] or compromise overall immunity.[49] Finally, there is no evidence of an immune-system role in autism.[44] The lack of evidence supporting the vaccine overload hypothesis, combined with these findings directly contradicting it, have led to the conclusion that currently recommended vaccine programs do not "overload" or weaken the immune system.[1][50][51]
In 1999, the Centers for Disease Control (CDC) and the American Academy of Pediatrics (AAP) asked vaccine makers to remove the organomercury compound thiomersal (spelled "thimerosal" in the US) from vaccines as quickly as possible, and thiomersal has been phased out of US and European vaccines, except for some preparations of influenza vaccine.[52] The CDC and the AAP followed the precautionary principle, which assumes that there is no harm in exercising caution even if it later turns out to be unwarranted, but their 1999 action sparked confusion and controversy that has diverted attention and resources away from efforts to determine the causes of autism.[52] Since 2000, the thiomersal in child vaccines has been alleged to contribute to autism, and thousands of parents in the United States have pursued legal compensation from a federal fund.[53] A 2004 Institute of Medicine (IOM) committee favored rejecting any causal relationship between thiomersal-containing vaccines and autism.[54] Autism incidence rates increased steadily even after thiomersal was removed from childhood vaccines.[44] Currently there is no accepted scientific evidence that exposure to thiomersal is a factor in causing autism.[55]
In the UK, the MMR vaccine was the subject of controversy after publication in The Lancet of a 1998 paper by Andrew Wakefield and others, reporting a study of 12 children mostly with autism spectrum disorders with onset soon after administration of the vaccine.[56] During a 1998 press conference, Wakefield suggested that giving children the vaccines in three separate doses would be safer than a single vaccination. This suggestion was not supported by the paper, and several subsequent peer-reviewed studies have failed to show any association between the vaccine and autism.[57] It later emerged that Wakefield had received funding from litigants against vaccine manufacturers and that Wakefield had not informed colleagues or medical authorities of his conflict of interest;[58] had this been known, publication in The Lancet would not have taken place in the way that it did.[59] Wakefield has been heavily criticized on scientific grounds and for triggering a decline in vaccination rates[60] (vaccination rates in the UK dropped to 80% in the years following the study),[61] as well as on ethical grounds for the way the research was conducted.[62] In 2004 the MMR-and-autism interpretation of the paper was formally retracted by 10 of Wakefield's 12 co-authors,[63] and in 2010 The Lancet's editors fully retracted the paper.[64]
The CDC,[65] the IOM of the National Academy of Sciences,[54] and the UK National Health Service[66] have all concluded that there is no evidence of a link between the MMR vaccine and autism. A systematic review by the Cochrane Library concluded that there is no credible link between the MMR vaccine and autism, that MMR has prevented diseases that still carry a heavy burden of death and complications, that the lack of confidence in MMR has damaged public health, and that design and reporting of safety outcomes in MMR vaccine studies are largely inadequate.[2]
In 2009, The Sunday Times reported that Wakefield had manipulated patient data and misreported results in his 1998 paper, creating the appearance of a link with autism.[67] A 2011 article in the British Medical Journal described how the data in the study had been falsified by Wakefield so it would arrive at a predetermined conclusion.[68] An accompanying editorial in the same journal described Wakefield's work as an "elaborate fraud" which led to lower vaccination rates, putting hundreds of thousands of children at risk and diverting energy and money away from research into the true cause of autism.[69]
A special court convened in the United States to review claims under the National Vaccine Injury Compensation Program ruled on 12 February 2009 that parents of autistic children are not entitled to compensation in their contention that certain vaccines caused autism in their children.[70]
There is evidence that schizophrenia is associated with prenatal exposure to rubella, influenza, and toxoplasmosis infection. For example, one study found a sevenfold increased risk of schizophrenia when mothers were exposed to influenza in the first trimester of gestation. This may have public health implications, as strategies for preventing infection include vaccination, antibiotics, and simple hygiene.[71] Based on studies in animal models, theoretical concerns have been raised about a possible link between schizophrenia and maternal immune response activated by virus antigens; a 2009 review concluded that there was insufficient evidence to recommend routine use of trivalent influenza vaccine during the first trimester of pregnancy, but that the vaccine was still recommended outside the first trimester and in special circumstances such as pandemics or in women with certain other conditions.[72] The CDC's Advisory Committee on Immunization Practices, the American College of Obstetricians and Gynecologists, and the American Academy of Family Physicians all recommend routine flu shots for pregnant women, for several reasons:[73]
Despite this recommendation, only 16% of healthy pregnant US women surveyed in 2005 had been vaccinated against the flu.[73]
Aluminium compounds are used as immunologic adjuvants to increase the effectiveness of many vaccines.[74] The quantities of aluminium ingested in this way are much smaller than the quantities ingested from other sources such as infant formula.[75] In some cases these compounds have been associated with redness, itching, and low-grade fever,[74] but its use in vaccines has not been associated with serious adverse events.[76] In some cases aluminum-containing vaccines are associated with macrophagic myofasciitis (MMF), localized microscopic lesions containing aluminium salts that persist up to 8 years. However, recent case-controlled studies have found no specific clinical symptoms in individuals with biopsies showing MMF, and there is no evidence that aluminium-containing vaccines are a serious health risk or justify changes to immunization practice.[76]
Other safety concerns about vaccines have been published on the Internet, in informal meetings, in books, and at symposia. These include hypotheses that vaccination can cause sudden infant death syndrome, epileptic seizures, allergies, multiple sclerosis, and autoimmune diseases such as type 1 diabetes, as well as hypotheses that vaccinations can transmit bovine spongiform encephalopathy, Hepatitis C virus, and HIV. These hypotheses have been investigated, with the conclusion that currently-used vaccines meet high safety standards, and that criticism of vaccine safety in the popular press are not justified.[51]
Compulsory vaccination policies have provoked opposition at various times from people who say that governments should not infringe on the freedom of an individual to choose medications, even if the choice increases the risk of disease to themselves and others.[3][77] If a vaccination program successfully reduces the disease threat, it may reduce the perceived risk of disease enough so that an individual's optimal strategy is to refuse vaccination at coverage levels below those optimal for the community.[78] Exempting some people from mandatory vaccination results in a free rider problem, in which a few individuals gain the advantage of herd immunity without paying the cost; too many exemptions may cause loss of herd immunity, substantially increasing risks even to vaccinated individuals.[79]
Vaccination has been opposed on religious grounds ever since it was introduced, even when vaccination is not compulsory. Some Christian opponents argued, when vaccination was first becoming widespread, that if God had decreed that someone should die of smallpox, it would be a sin to thwart God's will via vaccination.[6] Religious opposition continues to the present day, on various grounds, raising ethical difficulties when the number of unvaccinated children threatens harm to the entire population.[79] Many governments allow parents to opt out of their children's otherwise-mandatory vaccinations for religious reasons; some parents falsely claim religious beliefs to get vaccination exemptions.[80]
The cell culture media of some viral vaccines, and the virus of the rubella vaccine, are derived from tissues taken from therapeutic abortions performed in the 1960s, leading to moral questions. For example, the principle of double effect, originated by Thomas Aquinas, holds that actions with both good and bad consequences are morally acceptable in specific circumstances, and the question is how this principle applies to vaccination.[81] The Vatican Curia has expressed concern about the rubella vaccine's embryonic cell origin, saying Catholics have "...a grave responsibility to use alternative vaccines and to make a conscientious objection with regard to those which have moral problems."[82] The Vatican concluded that until an alternative becomes available it is acceptable for Catholics to use the existing vaccine, writing, "This is an unjust alternative choice, which must be eliminated as soon as possible."[82]
Many forms of alternative medicine are based on philosophies that oppose vaccination and have practitioners who voice their opposition. These include anthroposophy, some elements of the chiropractic community, non-medically trained homoeopaths, and naturopaths.[23] The reasons for this negative vaccination view are complicated and rest, at least in part, on the early philosophies which shape the foundation of these groups.[23]
Historically, chiropractic strongly opposed vaccination based on its belief that all diseases were traceable to causes in the spine, and therefore could not be affected by vaccines; Daniel D. Palmer, the founder of chiropractic, wrote, "It is the very height of absurdity to strive to 'protect' any person from smallpox or any other malady by inoculating them with a filthy animal poison."[83] Vaccination remains controversial within the profession.[84] Although most chiropractic writings on vaccination focus on its negative aspects,[83] antivaccination sentiment is espoused by what appears to be a minority of chiropractors.[84] The American Chiropractic Association and the International Chiropractic Association support individual exemptions to compulsory vaccination laws; a 1995 survey of US chiropractors found that about one third believed there was no scientific proof that immunization prevents disease.[84] While the Canadian Chiropractic Association supports vaccination,[83] a survey in Alberta in 2002 found that 25% of chiropractors advised patients for, and 27% advised against, vaccinations for patients or their children.[85]
Although most chiropractic colleges try to teach about vaccination responsibly, several have faculty who seem to stress negative views.[84] A survey of a 1999–2000 cross section of students of Canadian Memorial Chiropractic College, which does not formally teach antivaccination views, reported that fourth-year students opposed vaccination more strongly than first-years, with 29.4% of fourth-years opposing vaccination.[86]
Several surveys have shown that some practitioners of homeopathy, particularly homeopaths without any medical training, advise patients against vaccination.[87] For example, a survey of registered homeopaths in Austria found that only 28% considered immunization to be an important preventive measure, and 83% of homeopaths surveyed in Sydney, Australia did not recommend vaccination.[23] Many practitioners of naturopathy also oppose vaccination.[23]
Homeopathic vaccines are recognized as ineffective and dangerous due to their lack of immune system stimulation.[88]
Critics have accused the vaccine industry of misrepresenting the safety and effectiveness of vaccines, covering up and suppressing information, and influencing health policy decisions for financial gain.[3] Conversely, many groups profit by promoting the controversiality of vaccines, such as lawyers who receive fees often totalling in the millions of dollars, expert witnesses paid to provide testimony and to speak at conferences, and practitioners of alternative medicine offering expensive medications, supplements, and procedures such as chelation therapy and hyperbaric oxygen therapy.[89]
In the late 20th century, vaccines were a product with low profit margins,[90] and the number of companies involved in vaccine manufacture declined. In addition to low profits and liability risks, manufacturers complained about low prices paid for vaccines by the CDC and other US government agencies.[91] In the early 21st century, the vaccine market greatly improved with the approval of the vaccine Prevnar, along with a small number of other highly-priced blockbuster vaccines such as Gardasil and Pediarix that each provided sales revenues of over $1 billion in 2008.[90]
The US Vaccine Injury Compensation Program (VICP) was created to provide a federal no-fault system for compensating vaccine-related injuries or death. It is funded by a 75 cent excise tax on vaccines sold in the country and was established after a scare in the 1980s over the DPT vaccine: even though claims of side effects were later generally discredited, large jury awards had been given to some claimants of DPT vaccine injuries, and most DPT vaccine makers had ceased production. Claims against vaccine manufacturers must be heard first in the vaccine court.[53] By 2008 the fund had paid out 2,114 awards totaling $1.7 billion.[92] Thousands of cases of autism-related claims are pending before the court, and have not yet been resolved.[53] In 2008 the government conceded one case concerning a child who had a pre-existing mitochondrial disorder and whose autism-like symptoms appeared around the same time the child was vaccinated.[93]