Introduction:
Vaccination has been in use for over 200 years. The vaccines created to date have eradicated diseases, and have greatly contributed to extending the average life span of humans. Yet, for all it’s worth, there remain critic of vaccines who claim that they are harmful despite all the evidence to the contrary. To fully understand the problem, it is best to start at the beginning with the origins of vaccination.
In 1796, Edward Jenner created the first vaccine for smallpox. Jenner observed that milkmaids were immune to smallpox, but developed pox on their hands from the cows they milked. By taking material from the cowpox blisters of a milkmaid, he immunized a young boy against smallpox and helped create the new field of vaccinations. The name itself, “vaccine,” is attributed to Jenner. His vaccine came from cows, or vacca in Latin, and was named for this fact.
Louis Pasteur went on to elaborate on Jenner’s work. Pasteur found that rather than using a material similar to the infective one,such as cowpox to immunize for smallpox, the causative agent could be attenuated, or decreased in virulence. Pasteur first discovered this new method while working with cholera in chickens. Due to a laboratory mistake, spoiled cholera cultures were used in an experiment with the chickens. The spoiled cultures would not kill the chickens, and in fact protected them from the disease. Pasteur also created a vaccine to rabies using the same principle of attenuation. By growing the rabies virus in a rabbit, which is an abnormal host, he could use the dried rabbit spines to vaccinate others. The discovery of attenuation paved the way for the creation of many new vaccines.
Today, vaccines come in a variety of types that aim to maximize the immune response and safety. Pasteur’s principle of attenuation is still used to create live attenuated vaccines. The microorganism is grown in such a way as to lose its virulence and then injected into humans to create an immune response. These vaccines are very effective and require only one dose to create full immunity. However, the fact that they are still live, replicating organisms poses specific threats. First, the microorganisms could revert back to their virulent state, causing disease. Also, live vaccines tend to be costlier and cannot be kept for extended periods of time, in case they do revert back to a virulent state. In the 1950’s another problem arose with live vaccines; contamination. Polio virus was at the time attenuated in monkey cells. The monkey cells used were found to also contain another virus, SV40. Scientists found that SV40 could cause cancer in mice which created a public scare. Fortunately, it was later demonstrated that in both monkeys and humans the virus was non-transforming. The problems with SV40 contamination helped better the creation of vaccines and ensure that contaminants were not in cell lines to make the vaccines safer.
A safer form of vaccines is the inactivated vaccine. Unlike the live attenuated variety, inactivated vaccines are made of killed microorganisms. The use of dead microorganisms alleviates the worry that they may revert back to their virulent form. The safety of inactivated vaccines as well as their ease in storage are advantages over the live attenuated form. Yet, there are disadvantages to using killed microorganisms; they do not activate the immune system to the same extent that live microorganisms do. This means that boosters are required, as exemplified by the vaccine for the black plague. Its efficacy only lasts 6 months and it must be re-administered to ensure immunity.
Toxoid vaccines do not contain entire microorganisms. These provide specific protection against the toxins that the microorganism excretes. Toxoid vaccines are used for cases where the toxin causes the major pathology, not the organism. One such organism is the causative agent of diphtheria, Corynebacterium diphtheria. Its toxin is a powerful inhibitor of protein synthesis which can be lethal. Because this vaccine is specific for toxins, the range/variety of organisms it can be made for is limited. Toxoid vaccines work by inactivating the toxin while keeping it in its antigenic shape. The inactivation is often achieved chemically with reagents such as formaldehyde. Antibodies produced in response to this vaccine will recognize the toxin during infection and neutralize it before damage can be inflicted. One major drawback is that this vaccine will not hamper the growth and spread of the microorganism, only the pathology.
Subunit vaccines are the newest type developed. They use a small fragment of the whole organism, eliminating the risk associated with whole, live organisms, and making it very safe to use. The antigenic portion can be purified from the organism, which is the case in the vaccine against S. pneumonia. The antigen may also be derived by creating a recombinant protein such as the Capsid S protein used in vaccines for Hepatitis B. The antibodies produced in response to these antigenic proteins can bind, and neutralize the live microorganism.
The creation of vaccines is by no means exhausted and there are new methods being fashioned to prevent infections. DNA vaccines are one such new idea still under development. Instead of injecting the organism or an outer portion of the organism, a DNA plasmid is injected instead. When transcribed, this genomic vector produces the antigenic proteins. This system involves a two-fold approach to stimulating the immune system. Not only do the antigens made stimulate the creation of antibodies, but the DNA itself acts as a TLR agonist activating cell-mediated immunity. DNA vaccines would be easy to make and store because the DNA is so stable. Producing DNA is also cheaper than producing recombinant proteins. Currently, researchers have not been able to illicit more than a weak antigenic reaction in humans, which will need to be optimized. Unfortunately, there remains one major risk associated with this vaccine; injecting DNA could create an autoimmune response, and a Lupus-like disease against the host DNA.
To maximize future vaccines, as well as those is use, it is important to understand the mechanism of action of the components injected and how they trigger the immune system. The basis is very simple; it dictates that when the immune system sees an antigen it can generate two types of response, either humoral or cell-mediated. The next time the immune system comes into contact with the antigen, it is capable of creating a robust immune response, protecting the host. Vaccines tend to trigger a humoral, or Th2 response which is primarily mediated by antibodies. Antibodies produced will bind to their corresponding antigens and opsonise them for phagocytosis and complement activation, prevent cell adhesion or entry, or neutralize them in the case of toxins. Th2 responses are ideal for most bacterial infections as many bacteria are extracellular and therefore easily accessible to antibodies. However, there are intracellular pathogens, including viruses and certain bacteria, which are inaccessible for antibodies. Once the organism is inside the cell, a Th1 or cell-mediated response would be more effective. Th1 responses upregulate NK cells, and activate Jak-STAT pathways to induce anti-viral states in cells.
Sometimes, the antigens used in vaccines are not strong enough on their own to trigger a large enough immune response to produce immunity. For this reason, adjuvants can be added to help stimulate the immune response. Currently, alum is the only approved adjuvant in North America. Alum consists of an aluminum salt that helps trigger a Th2 response, but only creates a poor Th1 response. It is very efficient at helping to produce antibodies for antigens that can be accessed extracellularly. There are Th1-stimulating adjuvants, but they have yet to be approved for use in vaccines. Freund’s adjuvant could be a new possibility for vaccines as, depending on if it is the complete or incomplete form, it can create either a Th1 or Th2 response, respectively. While Freund’s adjuvant works very well, it cannot be used because of its high toxicity in humans. There are many other adjuvants currently undergoing research such as TLR-agonists, a form of Th1 adjuvants. Different molecules that could trigger TLRs include unmethylated DNA, lipopolysaccharides, or flagellin. Subunit vaccines would particularly benefit from a Th1 adjuvant as a protein by itself cannot signal through TLRs.
MMR and Autism:
Since Jenner’s time, there have always been groups of individuals opposed to vaccination. In Jenner’s case, some people thought that because cowpox was used, they would develop cow-like features and characteristics, or “bestial humors.” Others created only slightly more scientific arguments. Dr. Moseley was one of the first to criticise vaccinations in his 1798 work entitles “A Dissertation on Sugars.” Despite having the knowledge of how the vaccine worked, he went on to provide his opinion which was decidedly against vaccines. Jenner was famously quoted as saying “Moseley’s pen has killed more than Bonaparte’s sword.” During hearings at the House of Commons three years later, Moseley was forced to admit that he knew of no cases in which Jenner’s vaccine had failed to produce immunity or cause smallpox. In 1804, Goldson continued the controversy when he published a paper finding six cases of smallpox forming after vaccination. His claims were disproven as half his cases had not received the true cowpox vaccines, while the other half had not contracted smallpox, but a similar disease. The idea of becoming cow-like from a vaccine is now absurd, just as making groundless accusations or publishing poorly collected data is as well. Nevertheless, equally absurd theories persist despite scientific evidence to the contrary. One of the vaccines that has attracted much of the ire of the public is MMR.
MMR is a vaccine given during childhood to prevent measles, mumps, and rubella. The shot is given once at the age of one, and again before children start school around the age of six. It consists of three live attenuated viruses, so while there is a need for a second shot it is not a booster. The second shot is for the small percentage of children who fail to acquire immunity to measles during the first immunization. All three diseases prevented by MMR were endemic worldwide and caused severe morbidity and mortality in children.
Measles was particularly prevalent before the vaccination era/period, and at one time thought to be “as inevitable as death and taxes.” (Babbott) It is a virus that enters via the respiratory tract and can lead to diarrhea, or more importantly pneumonia or subacute sclerosing panencephalitis (SSPE). In developing countries the mortality can be up to 28%. Measles is also a highly contagious disease. Those infected can continue to transmit the disease for 3-5 weeks after the characteristic rash appears.
Mumps is far less lethal than measles, but still endemic worldwide and highly transmissible. Infected individuals are contagious six days before symptoms occur until nine days after symptoms occur. Death is unusual as mumps is generally self-limiting, but sequelae do occur. Most notably in men, orchitis can occur. This inflammation of the testicles is more severe in grown men and can lead to sterility.
Rubella is the last component of the MMR vaccines and like mumps, it is mild and self-limiting. However it is also highly contagious, and highly prevalent. The major concern is congenital rubella which occurs when a pregnant mother develops the disease. While the rubella virus/infection is not particularly harmful to the mother, the foetus she carries can be severely affected depending on how far along she is in her pregnancy. Rubella will not cause severe problems if contracted during the last trimester, or the first twenty weeks of gestation, but if it is acquired during the first or second trimester, there can be severe congenital defects ranging from cataracts, and deafness, to mental retardation.
Originally, all three childhood diseases had their own vaccine, but for the ease of children, they were combined into one. Like all vaccines, adverse effects can occur. A small percentage of children experience malaise and temporary joint pain. In rare cases, anaphylaxis can occur, but this is primarily an allergic reaction to eggs, which are used to cultivate part of the vaccine. When the decision to vaccinate children is made, one must remember that side-effects are present in almost all medical treatments. For vaccines, side –effects are often mild and happen only in a minority of cases. Unfortunately, there are groups that claim that MMR causes a much more direct side-effect; autism.
One of the principle problems with this argument is the ill-defined nature of autism. Autism is a brain development disorder often characterized by poor social interactions and communication. Autistic children can have a wide spectrum of social impairment ranging from mild (Asperger syndrome) to a much more severe autism. Symptoms of autism can include repetitive or compulsive behaviour, poor social skills, and an inability to communicate. These symptoms will generally manifest by the age of three.
The proposed causes of autism are numerous, but its theory of causation has yet to be cemented. Genetics has clearly shown a role in the heritability of autism, but even the genes that are inherited cannot be agreed upon. Only a small number of cases can definitively be attributed to genetics and these are generally related to allele deletions. Geneticists have suggested that between fifteen to one hundred different genes contribute to autism. The more common theory is that genetic background can predispose someone to autism, but an environmental insult is needed to stimulate the developmental disorder. (Trottier)
The environmental factor is another area that seems to show promise as a cause of autism. Prenatally, the only factor with convincing evidence is exposure to birth defect agents during the first 8 weeks after conception. (Szpir) The perinatal environment also shows a link to autism, although this could be purely causal. Such risk factors include low birth weight, hypoxia, and a short gestation period. Postnatally, multiple risk factors have been named but these are mostly anecdotal and lack any scientific evidence to back them up. These factors range from an autoimmune disease, to lack of vitamin D, to uncaring mothers, and include the theory that MMR causes autism.
While the causes of autism are not clearly defined, so too the diagnosis for autism is found somewhat lacking. The diagnosis for autism is made purely on behaviour as the exact cause and mechanism are currently unclear. Most diagnostic tools revolve around a semi-structured interview or observational period where doctors look for symptoms specifically associated with autism. Because of the anecdotal link with poor mothering, it is often difficult for families to accept that their children may have autism, and these children may wait longer before being brought in for a diagnosis. The stigma associated with autism has slowly been fading and a subsequent rise in autism rates has occurred. More people are aware of autism, its symptoms, and the diagnostic criteria, which could account of a significant portion of the increase in autism rates. The past few decades have also seen changes in the referral patterns, age of diagnosis, and availability of services to cope with autism.
The first proponent of the false association between MMR and autism was Andrew Wakefield. He ignited controversy with his 1998 paper published in The Lancet. The paper followed 12 children with developmental disorders and found that in 8 of the cases, symptom onset was linked with receiving the MMR vaccine. He found lymphoid swelling in the ileum of the children. This swelling, he hypothesized, was brought on by the vaccine which would weaken the intestinal lining allowing peptides to cross the barrier and eventually enter the brain, causing developmental disorders. Wakefield would go on to call this autistic enterocolitis.
The Lancet article sparked immediate controversy. In the months after its release, public trust in the MMR vaccine took a sharp turn, with an accompanying 12% drop in vaccination rates. During a press conference for his paper, Wakefield went on to recommend withdrawing the MMR vaccine from use in favour of single vaccines. The scientific community, roused by the suspicious conclusions found by the paper, went on to investigate his claims and found that Wakefield not only had a hidden agenda, but serious problems with his data collection.
The first suspicious aspect of the paper was the subjects themselves. The children taken for the study were by no means a random sampling, nor did they include a single control subject. In fact, the children had been recruited by lawyers who were preparing a lawsuit against the manufacturers of the MMR vaccine, Glaxo-Klein-Smith. The law firm contributed to the project funding by donating £55,000. The donation constituted a major conflict of interest but was never reported to board ofthe hospital. Wakefield personally took £440,000. At the time of the paper’s release, he had also applied for a patent on a measles vaccine that would be in direct contention with the MMR vaccine. His behaviour and actions clearly indicated a hidden agenda to promote his own potential vaccine while undermining trust in his competition.
As the controversy grew, more details continued to come to light about the methods used to obtain the results for the paper. Ethically, his research had been poorly conducted. All twelve children were given colonoscopies, colon biopsies, and lumbar punctures without proper approval, and completely contrary to the children’s interest. The data used from the children had in turn been manipulated and misreported. When parts Wakefield’s data was found to be in opposition to his central hypothesis, they were simply excluded from the publication. One example of this type of misrepresentation is the fact that gastrointestinal symptoms did not predate the autism in several children. Wakefield published an extremely biased and poorly conducted paper, and went on to publicize it in the media, grossly exacerbating the situation.
As with any major story, the media plays a crucial role in how the public perceives the problem. The media was quick to mount a story citing the MMR vaccine as a causative agent for autism and although media reports also emerged covering papers that proved the allegations false, they were roundly ignored by much of the public. The reasons why the negative Wakefield paper received more attention could be numerous. Generally, journalists will only read the discussions of scientific literature because it is less technical and less statistical. Between Wakefield’s paper and a sampling of a paper refuting his claim, Wakefield had a discussion section that was more accessible to the layman. By being written in a more accessible manner, Wakefield’s paper had a higher chance of being reviewed by journalists and news anchors with a less scientific background.
The news articles often quoted the articles and press releases to create a sense of authority, but by sampling some of these articles it is clear that the use of language had a significant impact how statements are perceived. The clearest example comes from a comparison between a BBC News article and an article in The Guardian. Both used an indirect quote from Deputy Chief Medical Officer Professor Jeremy Metters which stated that it would be impossible to completely disprove the link between MMR and autism, purely from a scientific view point. The BBC used a neutral tone by saying, “Metters said it was impossible to completely disprove a link between MMR and autism...” while The Guardian phrased it as: “Metters admitted that it was never possible to prove conclusively that something did not have an adverse effect.” The Guardian’s statement implied, however indirectly, that Metters was mistaken in some aspect of his work, giving the story a more negative association. The phrasing of the articles clearly impacted the public’s view of the issue.
The media also tends to polarize stories into a simple matter of good vs. Evil, right vs. wrong. Wakefield’s original press release defied the medical establishment, and the government health policy. To the media this conjured an image of the sole voice of reason, speaking out against the government’s rule. In short it projected a hero stereotype. Wakefield’s paper came soon after an inquiry as to the safety of vaccines if they contained bovine material. This inquiry was created due to the presence of BSE, or mad cow disease, in Britain. Wakefield’s study came out in a period where there was already mistrust in the government and vaccines making it a prime time for wide public acceptance.
Prevailing Theories:
Theory 1: Intestinal Inflammation
Since Wakefield’s paper, many anti-vaccine groups have sprung up. The unfortunate fact is that despite Wakefield’s paper being proven fraudulent, the public has continued to create scientifically un-backed theories as to why children should remain unvaccinated.
One of the first theories took its cue directly from Wakefield’s paper, and directly links MMR to autism with the claim that the vaccine damages the intestinal lining. The theory states that the vaccine causes inflammation to the intestines. The inflammation allows a peptide that cannot generally cross the barrier of the gut epithelium to enter the blood stream, and eventually the brain causing developmental damage. One of the many problems with this theory is timing. The MMR vaccine is given at approximately the same age that symptoms of autism occur. This type of argument is a logical fallacy known as “post hoc ergo propter hoc” or “if not before, then after”. A simple sampling of data showed that this was a coincidental correlation. During 1998, 1 in 2,000 children, or about 25 children were diagnosed with autism shortly after being vaccinated by chance alone. While that in itself is rather damning evidence, still more evidence exists to disprove this theory. Neither measles, mumps, nor rubella has been found to cause inflammation in the intestines, much less a loss of barrier function. Lastly, the peptide that would cross into the brain has never been identified. In fact, one of the possible genes involved in causing for autism codes for an endogenous protein which affects neurons in the brain. This protein would in no way come from the GI tract.
Although there was no scientific proof to back the concept, many studies were conducted to test the theory, and set parents minds at ease. Studies focused on the fact that if the MMR vaccine causes autism, then rates should correspondingly rise in countries after MMR was implemented. In the UK, studies found that vaccination rates were the same for autistic and non-autistic children. While they found that autism rates did not change with respect to instituting the MMR vaccine in 1987, autism rates did increase by year of birth. This increase was due to changing diagnostic tools and awareness of the disease. A study in Quebec also supported the conclusion that this theory was false. They found that the autism rates, like in the UK, had risen but the vaccination rates had actually decreased.
Theory 2: Mercury Poisoning
The first theory is very specific to the MMR vaccine in particular, but other theories exists which insist that not only MMR, but all vaccines can cause autism. These arguments focus on products found in most vaccines, specifically a derivative of mercury; thimerosal. Thimerosal has been used in vaccines for over 50 years although it is not used in live vaccines, such as MMR. These arguments focus on products found in most vaccines, specifically a derivative of mercury; thimerosal. It is primarily used as an antiseptic and anti-fungal agent which helps to preserve vaccines. The effect of removing such a preservative was clearly shown in 1928 when over half of a group of children vaccinated against diphtheria contracted Staphylococcus infections and subsequently died. Because thimerosal is a derivative of mercury, a toxic metal, there is legitimate concern about safety. It is true that thimerosal can be toxic if inhaled, ingested, or put on the skin. However thimerosal is injected into the body where it is rapidly metabolized into ethylmercury and thiosalicylate. In the body, ethylmercury is rapidly cleared, mostly in the feces. The amount given during injections can be cleared from the body within a week.On the other hand, its more deadly counterpart, methylmercury, accumulates in the body.
The government has always kept track of amounts of mercury in any product. Initially, in 1997, the FDA mandated that the presence of any amount of any mercury compound should be listed as product information in all food and drugs. Then in 1999 the FDA found that children could be receiving up to 187.5µg of mercury in the first 6 months of life from childhood vaccines. As a precautionary measure, the American Academy of Pediatrics and the Public Health Service recommended that thimerosal be removed from vaccines. This action was taken despite the fact that no evidence existed about the levels of ethylmercury in children having any adverse effects. The removal of thimerosal occurred soon after the Wakefield paper, which exacerbated the situation with anti-vaccine groups and caused increased public fear that vaccines were unsafe for children.
The scientific facts were again in direct contention to the idea that the mercury was causing developmental disorders. While methylmercury can cross the blood brain barrier and cause damage, the symptoms are very different. The changes to motor function, speech, and head circumference are vastly different. Mercury poisoning will cause many symptoms including profuse sweating, high blood pressure and heart rate, muscle weakness, and desquamification, none of which are consistent with the symptoms of autism. Conversely, ethylmercury was never shown to damage the CNS. The most important fact was later provided by the CDC when they found that mercury from vaccines did not create any signs or symptoms of mercury poisoning.
Once again, there was no scientific merit to the argument that thimerosal caused autism, but multiple groups created studies to dispel the notion. Both Sweden and Denmark conducted studies during the period of thimerosal use (1980-1990) and found that the rates of autism and thimerosal use were stable. This period included years when the mercury intake was as much as 200µg which is a very similar figure to that of the FDA. From 1990 to 2000, autism rates on both countries did increase but this cannot be linked to thimerosal as in 1992 it was removed from vaccines. Again this increase is most likely from higher awareness and diagnostic tools. A Quebec survey found similar results to suggest that thimerosal was in no way related to autism. They concluded that the groups with the highest rates of autism were the groups given thimerosal-free vaccines. If any conclusion were to be drawn from these studies, it would be that the absence of thimerosal caused autism.
Theory 3: Multiple Vaccines
After the theories of mercury poisoning and intestinal inflammation were discarded by the scientific community, groups convinced that vaccines were the cause of autism developed new theories to back their claims. What is now the most prevalent theory among anti-vaccine groups is that children are given too many vaccines too soon. This overwhelms and weakens the immune system, then goes on to interact with the central nervous system causing autism. Advocates of this theory do not all aim to abolish vaccines, many want only to space out the injection schedule. While this is certainly less harmful to children than abolishing vaccines, they will be vulnerable to preventable diseases for an extended period of time, increasing the risk of outbreaks.
It is true that in the past few decades the number of vaccines available for children has greatly increased. However, this theory vastly underestimates the ability of the immune system to react, particularly the naive immune system of a baby or infant. Children’s immune systems are capable of dealing with an incredibly vast array of pathogens. Children are, in fact, the age group that most rapidly and easily transmits viruses and bacteria because they are often exchanging bodily fluids from spitting, touching, and generally being in close contact with adults or other children. A child’s immune system will face far more pathogens than those given in vaccines. In addition, vaccines used today are far safer and use fewer antigens due to the use of adjuvants. In comparison, in 1980, seven vaccines were given which used upwards of 3,000 antigenic molecules. Today, 14 vaccines are administered using less than 200 antigenic molecules. If anything, the vaccines today are easier for the immune system to handle.
Despite its lack of scientific ground/credibility, the theory gained momentum when a compensation program for vaccines conceded that a 9-year old with mitochondrial enzyme deficiency and encephalopathy which included features of autism had worsened after being given multiple vaccines at 19 months. The young girl could have worsened after the vaccinations, but it is important to remember that she had a pre-existing condition. Therefore the only conclusion that can be drawn from the case is that children with mitochondrial enzyme deficiencies may experience adverse effects from vaccines.
It is true that in the past few decades the number of vaccines available for children has greatly increased. As already mentioned, the immune system of a child is more than up to the task. In addition, vaccines used today are far safer and use fewer antigens due to the use of adjuvants. In comparison, in 1980, 7 vaccines were given which used upwards of 3,000 antigenic molecules. Today, 14 vaccines are administered using less than 200 antigenic molecules. If anything, the vaccines today are easier for the immune system to handle.
The claim that the vaccines overwhelm a naive immune system can be easily cast aside by looking at the immune responses of children who have and have not received vaccines. The response to viruses and bacteria are equal in both groups suggesting that there is no weakening. However, diseases that are preventable by vaccine can predispose infected children to infection by other agents, which is why it is important to pursue with vaccination progams.
While one may logically think that giving combination vaccines like MMR might create an immune response equal to three separate vaccines, this is not the case. The single and combination vaccines produce immune responses of the same magnitude. The idea that too many vaccines weaken the immune system implies that autism is an autoimmune reaction. However in autistic patients, there has yet to be any evidence of inflammation or immune activation in the central nervous system.
Currently, there are no studies done to test this theory by comparing autism rates in vaccinated, unvaccinated, and alternatively vaccinated children. Such a study would face difficulties because of the differences in life style, and health care in these groups of children.
Transmission of anti-vaccination theories:
The media in the form of news papers, radio, and television are responsible for propagating the theories that link MMR to autism. But there is another source of information not normally considered; celebrities. Celebrities often use their status to speak to others about issues they are passionate about, and this has had an impact on the battle over vaccines. Jenny McCarthy represents one of the celebrities who have chosen to speak out. McCarthy is an actress and, more recently, an anti-vaccine advocate. Her desire to spread her concern about vaccinations occurred after she self-diagnosed her young son with autism. She noticed symptoms that she associated with autism shortly after her son was vaccinated with MMR, and came to the conclusion that the symptoms were a direct result of his vaccination. From this point on, McCarthy decided to join those opposed to vaccination of young children and became a spokesperson for Talking About Curing Autism. McCarthy’s theory of choice was that the mercury in her son’s vaccine had triggered his autism. She brought her son to Canada to undergo a chelation therapy and shortly after, declared her son had overcome his autism and was cured.
McCarthy represents a risk to keeping vaccination levels high over the coming years. She uses arguments that are known to be false, to have no scientific backing, and is spreading them widely using her celebrity status. As already mentioned, the mercury in vaccines does not cause any side-effects in children, least of all autism. Autism is also not a curable disease at this point in time. In fact the symptoms displayed by her son, which began with seizures, were more consistent with Landau-Kleffner syndrome, an affection often misdiagnosed as autism. The idea that she cured an incurable disease by treating her son with something to remove mercury, that also didn’t cause the disease, is laughable at best. Yet she remains a strong anti-vaccine advocate spreading her ideas to those willing to listen.
So far, all the modes of transmission of the theories have directly utilized media in one form or another. Nevertheless low uptake of vaccines can also be linked to religious worship in communities where there can be much less media input. The orthodox Jewish community is one such group with relatively low levels of influence from outside media sources, being a very closed community. In the City and Hackney area of east London, the Orthodox Jewish community has the lowest vaccination rate of any other ethnicity at just 46%. Most information regarding vaccines in these communities was passed along through word of mouth and anecdotal stories. Families in the area were polled about why they did not vaccinate as often. Surprisingly, there was a strong value placed on vaccines, as the Jewish religion holds good health in high regard. But this high regard does not translate into vaccination rates. It was found that in the large families it was rare for all children to be vaccinated. Generally only the older siblings had received the vaccine.
The consensus in the community was that it was so insular that they were at a low rate of newcomers bringing the disease in at all. This feeling of safety has in large part caused the extremely low rates of BCG vaccination which has become such a long-standing practice that it has been given the status of a “Jewish belief.” What these communities fail to take into account is that many childhood diseases, especially measles, mumps, and rubella, are highly communicable and could be acquired from something as simple as being sneezed on at the supermarket. The families were also very fatalistic about their children suffering from diseases. They claimed that if their child was destined to catch the disease, it would happen either way. What these communities fail to take into account is that many childhood diseases, especially measles, mumps, and rubella, are highly communicable and could be acquired from something as simple as being sneezed on at the supermarket. For this religious group it is the false sense of safety combined with the sense of potential danger from vaccines that keeps vaccination levels low.
After reviewing the best known theories of vaccination and autism, all three have no scientific basis. The theories of intestinal inflammation and mercury poisoning have been thoroughly discredited, but there somehow remain those who believe they are true. The theory of multiple vaccines has been less thoroughly disproven despite being false and remains a significant hurdle in convincing parents that vaccines will not harm their children. Proponents of these theories argue that they should have the right to not vaccinate their children. They point out that the only people they would possibly harm are their own children and no one else. These people may believe they are not hurting anyone else, but the fact of the matter is that other children will suffer because of the action of these groups of parents. They risk higher numbers of outbreaks of disease, and they decrease the herd immunity as can be clearly seen when looking at countries where anti-vaccine groups are prevalent.
Case studies:
Vaccinating a population against diseases is most effective when all, or almost all of the members are vaccinated, creating herd immunity. The idea of herd immunity is that the possible reservoirs for a disease will be wiped out.So not only will diseases not be able to infect those vaccinated, but the reservoir pool will be insufficient to sustain the disease’s transmission. When those opposed to vaccines refuse to vaccinate their children, the herd immunity is weakened, putting countries at risk of developing disease outbreaks, and ultimately becoming endemic.
To measure how close a population is to developing high numbers of outbreaks, a reproductive number (R value) is used. R values measure the mean number of secondary infections per infection. In general, the R value is proportional to the fraction of the population that hasn’t been immunized and are likely to be susceptible to infection. An R value less than 1 is ideal, although the closer to 0 the better. If it is under 1, there are only periodic outbreaks, usually by disease importation. In these cases, people from other countries considered endemic are generally implicated either from immigration or travel history. An R value of 1 is termed criticality. Any value above 1 denotes large outbreaks, and reflects the possibility that the disease will become endemic in the population.
Europe has for the past 20 years been vaccinating for measles and had set the date for eradication at 2010. However in 2006 and 2007, several countries showed high numbers of outbreaks. These countries were Romania, Germany, the UK, Switzerland, and Italy. Approximately 45% of the cases of measles were in children under the age of five with an average of only 80% of the population taking the MMR or single measles vaccine. In each case, the amount of measles outbreaks was directly related to the amount of vaccination.
One common argument used by parents in these European countries is that vaccines introduce diseases into the community where they are not often found. Their argument follows the logic of “if it’s not broken, don’t fix it.” Obviously the vaccines will not cause disease or harm the child, but the parents with this idea must remember that there is no prevalence of many vaccinated diseases because of the mass-vaccination campaigns. Should these campaigns now falter, populations everywhere risk the re-emergence of previously rare diseases. A sampling of online chat discussions in the UK revealed that this is still very much an issue in the community. The majority of users recognized that herd immunity played an important role in keeping their children safe, but there remained a minority who were not planning on vaccinating their children and who thought that there were not enough disease rates to warrant everyone needing vaccinations. The arguments presented by some users are no doubt the arguments of many who chose not to give the vaccines to their children.
United Kingdom:
England and Wales have been prime examples of the potential consequences that can occur when vaccine rates drop. During the period of time when Wakefield’s paper was released, vaccine uptake seriously decreased. Shortly following the decreased use in MMR, rates of measles began to increase. To be specific, the number of measles cases is now at the highest it has been in the last thirteen years. Each year since these events, the rates have increased. In 2007, 990 cases of measles were reported. In 2008 this number increased to 1348 cases. The bulk of these cases were, as can be expected, in children who had not received their MMR vaccine. However, it is not only the young children that have been affected. The anti-vaccine movements began years earlier, and as a result there are now many who missed their MMR vaccine as children and have yet to be inoculated against the three diseases. There is now a section of the population that is very susceptible to measles, mumps, and rubella. If women in this group go on to have children without being vaccinated themselves, they risk acquiring the rubella virus during pregnancy and passing on the congenital rubella syndrome.
It is easy to forget that the MMR vaccine did not only decrease the rates of measles, mumps, and rubella in the UK, but also those of SSPE. It is a slow progressing chronic disease that is often fatal, being a degenerative disease of the central nervous system. Once SSPE sets in, patients undergo a loss of cerebral function, paralysis, coma, and eventually death. The life expectancy is generally under three years. SSPE is caused by measles, often contracted during childhood or at a young age. The measles virus can persists in the brain, and eventually can cause this terminal illness. After measles rates dropped, the incidence of SSPE dropped accordingly a few years later.
Although there is still a low prevalence of SSPE, rates threaten to increase as the measles cases also increase. Localized outbreaks of measles have been found in England with several of the cases being in infants. These infants were too young to have received the MMR vaccine yet, therefore their infections could be due to a weakening in the herd immunity. Worst of all, the infants could succumb to SSPE in the following years, if the virus persists in their brain.
There is some good news in this situation; trust in the vaccine has been increasing. Now, eight out of 10 children in the UK are likely to have been vaccinated by the age of two. There are agencies in place to help catch up those who missed their vaccines, but the progress has been slow. Less than one quarter of those children who had missed their vaccine were able to be vaccinated. The low success rate is partially due to the fact that the campaign was held during the winter when there is high absenteeism in the children, as well as in the health nurses. This particular catch-up campaign was also planned quickly and was found lacking in certain areas such as training.
Finland:
The rate of measles in the UK serves as a cautionary tale for other countries. But not all countries have experienced this failure of vaccinations. Finland is a great example of a country who has done consistently well in keeping their population safe. Finland has a very old and very well-documented history of measles in the population. The churches kept highly accurate records of deaths and accompanying symptoms which allowed scientists to tract what was most likely outbreaks of measles. Between 1775 and 1810 measles epidemics occurred once every five to ten years. In 1986, the current version of MMR was introduced into the country and measles was declared eradicated. One year later, mumps and rubella were also declared eradicated. The MMR vaccine was distributed free of charge by public-health nurses, on a voluntary basis.
Occasional cases of measles still occur, but the government is quick to take action when these cases arise. The procedure begins with all potential measles cases being confirmed in laboratories. The patient with measles will then have their vaccine status checked and be interviewed about their past history of vaccination and travels. The cases can often be traced back to a specific endemic country, and sometimes to the infected individual who passed on the disease. The rare cases of measles in Finland are primarily imported from endemic countries, and occur in unvaccinated individuals.
While Finland has done phenomenally well in eradicating measles and ensuring vaccine uptake, new problems have arisen. In adults, the levels of antibodies have been declining over the years. This is due to waning immunity. Normally, when a disease is given as a vaccine, individuals will encounter the disease multiple times over their life span. These encounters serve as natural boosters to keep antibody levels up. When a disease is completely eradicated, there is no chance for the population to receive natural boosters and the chance that an adult could contract the disease increases over time. To deal with this problem, Finland may need to consider using boosters in parts of the older population.
Discussion:
The Wakefield paper and subsequent fallout shook the public trust in vaccines. During those years, uptake of vaccines dropped, and anti-vaccine groups sprang up in many countries. The levels of vaccination have been slowly climbing back to what they formerly were, but there is still a ways to go. As we fight to increase public trust in vaccines, it is time to look at what the future may hold.
Many children whose parents were opposed to the MMR vaccines have remained unvaccinated and are susceptible to disease and disease spreading. The UK has already taken steps to catch up on vaccinations but the results were less than ideal. The idea of catch-up campaigns was sound, and should be implemented in other countries to vaccinate those who did not receive the necessary vaccines. Health care providers can learn from the mistakes of the UK’s campaign. The new campaigns can include a longer, more encompassing planning time to address the issues of training, and distribution the vaccines.
It is important that populations master the distribution of current vaccines, as they face an increased number of diseases becoming prevalent in their areas. The number of diseases in developed countries could be on the rise and global warming impacts the planet. As the Earth warms, the geographic distribution of many vectors will increase. As vectors venture further in temperate regions, a higher percent of the population will be in disease endemic areas. Malaria could enter the United States if the distribution of Anopheles mosquitoes were to increase into North America. Likewise, West Nile Virus would penetrate further into Canada if its mosquito vector spread northward.
Unfortunately, tropical diseases like malaria, which are passed by vectors, often have no vaccine, and little funding for research because of the limited profit to pharmaceutical companies. For this reason, the global warming could be seen in both a positive and negative light. The obvious negative is that more people will contract tropical diseases. The silver lining is that as more people in developed countries contract disease, it will become more profitable for vaccines and new drugs to be made against them.
As we face the possibility of an increased number of diseases in developed countries, we must address how to reconstruct the public trust in vaccines. The scientific community has long been in agreement that vaccines cause almost no harm, and certainly have no association with developmental disorders such as autism. Scientists have produced more than enough proof of the lack of association. The focus must shift to the general public. The first step in rebuilding trust is to educate the parents. An ideal time frame would be during prenatal classes. Pregnant mothers could be given one short class to address the issue of vaccinations as well as answer the mother’s questions about negative side effects. The next step is to publicly address the anti-vaccine groups by engaging in public debate. In this fashion, the scientific data could be presented in an accessible way while directly assuaging the fears brought about by these groups. This type of debate would be viewed by many of those who are currently opposed or undecided about the issue of vaccination and allow them to make informed decisions. Public service announcements should be placed on television and radio by local governments to remind parents that it is essential to the population’s health that children be vaccinated.
In addition to helping parents understand the issue, it is critical that research into autism continues to grow. If the causes of autism could be pinpointed, better diagnostic tools could be made available. The current diagnostic tools are rather subjective, so a definitive laboratory test would be ideal for diagnoses, if possible before the onset of symptoms. This would allow for better treatment strategies.
Conclusion:
Overall, misinterpretation and misinformation about the issue of the MMR vaccine has been far too prevalent for far too long. Scientists have worked hard to clear the air surrounding vaccinations, but more remains to be done. The general public must understand the facts, while the governments and researchers must understand and address the concerns of parents. Once the parents of young children understand the issues, vaccine uptake will rise once more and populations will be better protected against diseases that hit the youngest and most vulnerable citizens in our society; the children.
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