This section looks at a number of the common and longstanding misconceptions about immunisation. Many additional issues may arise, and new evidence is constantly emerging, so it may be helpful to contact the Immunisation Advisory Centre (0800 IMMUNE / 0800 466 863) for more detailed information on specific concerns. There are also some suggestions at the end of this section for locating helpful commentary and rebuttals to new myths and concerns as they arise.
There are many claims that vaccines cause long-term adverse effects, such as chronic immunological and neurological disorders. Examples of these disorders are autism, attention deficit disorders, asthma and eczema, chronic fatigue syndrome and other autoimmune disorders. There have been many studies addressing these issues and they consistently demonstrate that vaccines are not responsible for any increased risk in these sorts of disorders. The most prominent claims in recent years are summarised below.
There is no evidence that the MMR vaccine causes autism.3, 4 Extensive scientific research has been devoted to this topic, resulting in an increasing body of evidence that childhood vaccination is unrelated to the development of autism.
In 1998 a British physician announced he had found a virus from measles vaccines lingering in the intestines of 12 autistic children, which he believed was related to autism. No subsequent studies following his study have been able to reproduce his results. In 2004 The Lancet published a retraction submitted by 10 of the 13 original authors of the 1998 study. The authors stated that there was no connection between the MMR vaccine and the bowel disease/autism syndrome.
In 2008 a press investigation revealed that the doctor had falsified patient data and relied on laboratory reports that he had been warned were incorrect. The Lancet retracted the original 1998 study from the scientific literature on the grounds that it was the product of dishonest and irresponsible research and the British authorities revoked the doctor’s licence to practise medicine.5 Studies exonerating the MMR vaccine continue to be published.
There are often claims that childhood vaccines have a role in the development of allergic disease. There have been many studies of different design that have explored this issue. A few have shown a positive association, but the majority show no association or a negative association. The international scientific community generally accepts that vaccines do not lead to allergies and in fact have a small protective effect against the development of allergy.6
It is especially important that children with asthma be given all recommended vaccines, as catching a disease like pertussis or influenza can worsen asthma.7 In New Zealand, influenza vaccination is particularly recommended for children with asthma because of this risk.
The possibility that MMR vaccine can cause allergic diseases has been raised. In 2005 and 2012 a Cochrane Systematic Review of the literature on vaccines for measles, mumps and rubella found no evidence that MMR increases allergic disease. 3, 8
The 2012 Institute of Medicine review of adverse events rejected any causal relationship between inactivated influenza vaccine and asthma exacerbation or reactive airway disease episodes in children and adults.4
The scientific evidence shows there is no association with autoimmune conditions.
Several large cohort studies have been conducted to investigate the link between HPV vaccine and autoimmune conditions.9, 10, 11, 12, 13 No association has been found in these studies.
There is no scientific evidence that links POTS, CRPS or CFS with HPV vaccination.
POTS is a condition in which tachycardia occurs when a patient moves from a supine position to upright. The condition is associated with a collection of other symptoms which include palpitations, light-headedness, weakness, blurred vision, headache, extreme fatigue, nausea, syncope and sleep disturbance. Up to 50 percent of people with POTS have an antecedent vial illness and 25 percent have a family history of similar complaints. There is an overlap between POTS and CFS.14
CRPS describes a variety of disorders characterised by pain that is disproportional to the inciting event. In children and adolescents it often presents as a painful mottled swollen limb with allodynia and hyperalgesia. Girls are six times more likely to be affected than boys and the peak age of onset is at age 12–13 years. Often minor trauma is the inciting event, but around one third of people with CRPS are unable to recall an inciting injury or trauma.15
CFS is a disorder characterised by extreme fatigue that cannot be explained by an underlying medical condition. The causes are unknown but it has been linked to infection with Epstein-Barr virus and human herpesvirus 6.
Cases of these disorders have been reported in association with HPV vaccination, particularly in the media, and social media. The variable time between vaccination and onset of symptoms, lack of consistent symptoms and a reporting rate that remains below the expected rate all point to HPV vaccine not being the cause of these conditions.16
Post-marketing surveillance systems globally continue to monitor the safety of HPV vaccination programmes.17, 18, 19 The WHO’s Global Advisory Committee on Vaccine Safety has systematically reviewed HPV vaccine safety and has not found any safety issue that would alter its recommendations for use.20 The main challenge with HPV vaccine is communicating its excellent safety profile.21
Sudden unexplained death in infancy (SUDI), also known as cot death, usually occurs in children aged under 12 months and is most common around age 3 months, when many immunisations are given. SUDI may occur by chance within a day or so of immunisation.22 There is no evidence that vaccination causes SUDI. Despite solid evidence against a link, the claims continue to be made.
There have been many studies that have conclusively shown that SUDI is not caused by immunisation.22 Some studies, including the New Zealand Cot Death Study, found a lower rate of SUDI in immunised children.23 This is consistent with a Scandinavian study, which found that some cases of SUDI were probably caused by undiagnosed pertussis.24 A large case-control study showed no increased risk of SUDI associated with immunisation,25 and a meta-analysis of nine case-control studies further suggested that immunisation is protective against SUDI.26 Consistent findings from several studies using a range of methods invalidate claims that associate vaccination with SUDI or cot death.
There is no evidence of immune system ‘overload’, either theoretical or actual. The immune system is able to deal with an extraordinarily large number of different antigens. Every day we all come into contact with viruses, bacteria and other agents to which the immune system responds. Any demands placed on the immune system by vaccines are minuscule compared to its ability to respond.
Furthermore, the number of immunogenic proteins and polysaccharides in modern vaccines has decreased dramatically compared with early vaccines because of advances in vaccine technology. For example, early whole-cell pertussis vaccines contained around 3000 immunogenic proteins, compared with two to ﬁve in the modern acellular pertussis vaccines. In spite of an increase in the number of vaccines on the Schedule, an infant now receives far fewer immunogenic proteins and polysaccharides than with earlier vaccines.27
From birth, an infant’s immune system responds to various microbial challenges in the environment. The infant is also able to generate an effective immune response to most vaccines; for example, infants born to mothers infected with hepatitis B virus are mostly protected against infection after receiving the hepatitis B vaccine given at birth (along with hepatitis B immunoglobulin) and at age 6 weeks, 3 months and 5 months.
Eighty-ﬁve to ninety-five percent of infants immunised against pertussis, diphtheria, tetanus, poliomyelitis (polio), Hib, pneumococcus and hepatitis B in the ﬁrst six months of life develop protective vaccine-speciﬁc antibodies. Conjugation of a vaccine antigen to a carrier protein (eg, Hib or pneumococcal conjugate vaccine) enables the infant to develop a speciﬁc immune response using helper T-cells, and therefore a speciﬁc T-cell memory. In contrast, infants and children aged under 2 years do not develop such protective immune responses following infection with wild organisms (eg, H. influenzae and S. pneumoniae).
Vaccine production is highly regulated, requiring extensive testing during manufacture and of the ﬁnal product (see section 1.6). The testing standards are rigorous and internationally regulated by independent authorities. The manufacturer must show that each dose is safe, refined and potent enough to be effective. The sophistication of this testing continues to improve, and modern technology enables the detection of single molecules of viral DNA or RNA.
There have been occasions when vaccines have become contaminated with unwanted viruses: avian leucosis virus in yellow fever vaccines, SV40 in polio vaccines in the 1950s, and pestivirus in some Japanese vaccines in the 1980s. Most recently, due to new technology, rotavirus vaccines have been found to contain DNA fragments of porcine viruses. In March 2010 the United States (US) Food and Drug Administration (FDA) temporarily suspended the use of RV1 (Rotarix) after porcine circovirus (PCV) was identified in commercial vaccine lots.28 Fragments of the PCV genome were also later identified in RV5 (RotaTeq). The FDA later resumed the use of RV1 and continues to support the safety profile of both vaccines.29
Any potentially toxic substances (eg, formaldehyde) present in vaccines are only permitted in trace amounts, too small to cause any harm, and usually in lower amounts than naturally occur during environmental exposure. The chances of modern vaccines becoming contaminated with harmful residuals is extremely low and the probability of detecting such contamination very high.
The rubella vaccine virus can only be grown in cell lines of human origin. A cell line is an ‘immortal’ self-replicating group of cells that can be maintained indeﬁnitely in the laboratory, providing a safe, standardised medium for growing vaccine viruses. Both the rubella vaccine cell line and the rubella vaccine virus were derived from fetal tissue in the 1960s. Once vaccine virus has been cultivated in cells, it is separated from cellular material and purified. If any cellular material remains in the vaccine, it is only in minute traces.
During the early stages of the HIV epidemic it was suggested that an early polio vaccine was cultivated in chimpanzee cells contaminated with the precursor of HIV-1, simian virus. It was claimed that the use of this polio vaccine resulted in the transfer of the virus to humans, and was the source of HIV. No chimpanzee tissue was involved in the production of this vaccine. Also, supplies of the early polio vaccine were discovered in freezers and tested in several laboratories, none of which found that HIV, or chimpanzee DNA, was present in the vaccine. Thus it has been convincingly demonstrated that polio vaccine was not the source of HIV.30
Aluminium is one of the most abundant elements on earth and has been used in vaccines for more than 70 years. An average daily exposure to aluminium is about 10–15 mg, most of which comes from foods. Humans and other mammals are constantly exposed to aluminium compounds, and as a consequence aluminium compounds are found in the blood of all humans and animals. Normally, aluminium compounds are excreted through the urine.
Aluminium compounds are used in some vaccines as an adjuvant (something that helps stimulate an immune response). Aluminium adjuvants have a long-established safety record, with a low incidence of reported adverse events. Minor reactions occur fairly often, but there have been very few serious reactions. Local reactions are more likely if the injection is delivered into the subcutaneous tissue rather than deep into the muscle.
Aluminium compounds administered via vaccination do not contribute significantly to the general aluminium exposure and do not raise human serum aluminium levels. Based on 80 years of experience, the use of aluminium adjuvants in vaccines has proven to be extremely safe and effective.31
None of the vaccines on the New Zealand National Immunisation Schedule contain thiomersal, including the current influenza vaccines.
Thiomersal (also known as thimerosal) is a mercury-based preservative used in some vaccines and other pharmaceutical products, such as antiseptics.
Mercury is a naturally occurring element found in the Earth’s crust, soil, water and the air and is released into the environment by volcanic eruptions, weathering of rocks and the burning of coal. Once released, mercury can find its way through the food chain via fish and other animals. At high levels it is toxic.
Some forms of mercury pose a greater health risk than others. For example, mercury vapour is extremely dangerous, whereas amalgam, used in dental fillings, has not been shown to pose any health risk. Ethyl mercury found in thiomersal has significantly less potential for toxicity than methylmercury (found in the food chain) because it is rapidly eliminated from the body and does not build up in tissues.
Thiomersal continues to be used in vaccines in many countries. The WHO’s Global Advisory Committee on Vaccine Safety (GACVS) has concluded that ‘there is currently no evidence of mercury toxicity in infants, children or adults exposed to thiomersal-containing vaccines’ and that ‘there is no reason to change current immunisation practices with thiomersal-containing vaccines on the grounds of safety’.
The duration of immunity varies with different diseases and different vaccines. Lifelong immunity is not always provided by either natural infection or vaccination. The recommended timing of vaccine doses aims to achieve the best immune protection to cover the period in life when vulnerability to disease is highest.
The duration of immunity following vaccination may be shorter than the duration of immunity induced by the disease (but not always). However, both are protective, and if immunity following immunisation wanes, booster doses can be given. Natural immunity and vaccine-induced immunity are both the result of the natural responses of the body’s immune system.
More importantly, those who suffer ‘natural’ disease run the risks of serious illness, disability and death to acquire their immunity. In contrast, the acquisition of vaccine-derived immunity is a much lower risk. However, several doses of vaccine, along with booster doses, may be necessary to attain and maintain good levels of immunity, and immunisation does fail in a small proportion of vaccinees.
For some organisms (eg, Hib in children aged under 2 years, HPV and tetanus at any age), the immunity following vaccination is better than that following infection. The Hib vaccine stimulates immune memory in infants in a way that the disease does not, and tetanus can be caused by a small amount of toxin that is insufficient to generate an immune response. In 1995 a 40-year-old man developed tetanus for a second time. He had failed to complete the recommended immunisation course after recovering from an earlier episode of tetanus (see chapter 19).
Improvements in living standards, in particular clean water, had a great impact on health during the 19th century. Apart from sanitation and clean water, no other public health intervention has had as great an impact on the decline of infectious diseases as immunisation.
Improvements in living conditions and medical care have reduced the chance of dying from infectious disease, but without immunisation most people will still acquire vaccine-preventable infections. For example, measles, which spreads through the air, is largely unaffected by improvements in living conditions other than reduced overcrowding. Indigenous cases of measles, mumps and rubella have been eliminated from Finland over a 12-year period using a two-dose measles, mumps and rubella vaccine (MMR) schedule given between 14 and 16 months and at age 6 years.32
Healthy children living in ideal conditions remain at risk of death and disability from infections that can be prevented by immunisation. Smallpox vaccination led to the elimination of smallpox, and polio vaccination has eradicated polio from most countries. This could not have occurred through improvements in living standards alone.
Another example of the impact of immunisation was seen in New Zealand, and elsewhere, following the introduction of the Hib vaccine in 1994. This led to a decline in Hib disease of approximately 95 percent – unrelated to any other change (see chapter 6). Conversely, when pertussis immunisation coverage dropped in England, Japan and Sweden in the 1970s, there were dramatic increases in pertussis disease and deaths.
There are many examples of resurgence of disease when immunisation is halted for some reason, or when whole communities are unimmunised. Examples include the following.
The role of immunisation is discussed in more detail in each chapter, but its overall impact on vaccine-preventable diseases has been well established. If high enough immunisation coverage could be attained, it may be possible to eliminate measles, mumps, rubella and Hib from New Zealand.
No vaccine is 100 percent effective and some immunised children will get the disease. As immunisation coverage increases, the proportion of cases that occur in children who have been immunised compared with those who are unimmunised increases. There is a mathematical relationship between vaccine effectiveness, immunisation coverage and the proportion of cases that are immunised.
To see this clearly, imagine a group of 100 children. If 90 percent of children are given a vaccine with 90 percent efficacy, then:
This means that in the situation of exposure to the infection in a community, we expect that nearly half the cases of disease will be in immunised children, even though only 10 percent of immunised children were susceptible.
Of course if all 100 children had been vaccinated only 10 would be susceptible to disease. As vaccine uptake rises, the proportion of cases of disease that occur in vaccinated people increases dramatically, but the absolute number of cases of disease falls to very low levels. Forgetting the denominators (how many vaccinated and how many unvaccinated) can lead to misunderstanding.
For pertussis, where the protection following immunisation lasts only four to six years, immunised children can be infected but the resultant illness is usually milder, with fewer serious consequences and at an older age than if they had not received vaccine. The disease is most severe in infants, but adolescents and adults contribute to the carriage and spread of the disease (see sections 14.2 and 14.3).
The claim that immunisation is harmful simply because it is artificial is not based on evidence or biological first principles. Some claim that the immune system was not designed to be exposed ‘directly’ to an antigen, in the manner of an injection. The immune system is extremely well equipped to respond to foreign antigens entering via a range of different routes in the body. Foreign protein is taken up and processed by the immune system very well when injected into muscle. The specific immune response occurs in lymph nodes regardless of the antigen’s mode of entry. An example is the injectable polio vaccine, which has been shown to work just as well as the oral vaccine (which enters the body in the same way as the infection).
A healthy lifestyle alone does not result in the necessary specific immune response occurring rapidly enough to protect a child from a potentially serious infection. Only immunisation or being infected by the organism can do this. Immunisation poses far less risk than natural infection because it is very unlikely to cause an illness, while those suffering natural infection are very likely to become ill.
The living arrangements of a person (eg, overcrowding, inadequate sanitation and hygiene) will affect the likelihood of exposure to infection. While those in good health will be less likely to suffer a severe illness or complications as a consequence of infection, a healthy lifestyle does not provide secure protection against infectious disease or its complications. Most hospitalisations in New Zealand for vaccine-preventable diseases are in previously healthy children.
Although breastfeeding reduces the frequency and severity of gut, respiratory and ear infections, there are many infections for which no protection has been demonstrated. The protection from breastfeeding is multifactorial, including passive immunity, which is dependent on the mother’s level of circulating antibodies, so it varies from woman to woman and is of brief duration. Breastfeeding is not an alternative to immunisation, and both contribute to the health of children. Of particular note is the fact that breastfeeding does not protect against pertussis infection.36
Some homeopaths do not support conventional immunisation and state that homeopathic preparations can prevent disease. There is no evidence that homeopathic ‘immunisation’ provides any protection against infectious diseases. The United Kingdom (UK) Faculty of Homeopathy supports conventional immunisation.37
The morbidity and mortality resulting from vaccine-preventable diseases is detailed in each disease chapter. Some people claim that measles is important for normal development and that after the illness children have a leap in physical and mental development. There is no evidence to support this, and given the serious impact of measles on a child’s health it is not surprising that a child who has recovered will appear to have much more energy than during the illness. On the other hand, there is evidence that a child has reduced immunity for weeks to months after measles, and during this time the child is more likely to get other infections.
For information for parents and guardians, including a comparison of the effects from disease and possible side-effects of vaccines, see the Ministry of Health resource Childhood Immunisation (HE1323; available from www.healthed.govt.nz or your local authorised resource provider) and the Resources page of the Immunisation Advisory Centre website (www.immune.org.nz).
In the past few years the internet has exploded with a variety of forums that disseminate anti-immunisation material effectively. It is no longer practical to prepare official rebuttals to each new article. Fortunately, the internet also facilitates the rapid communication of scientific commentary on new myths as they appear. There are several scientists who regularly address immunisation myths in the form of regular blogs. In addition, some organisations provide position statements and discussion forums.
Below are some organisations and individuals who write and provide information related to immunisation scares, myths and pseudoscience. They can be a source of new information that may help to address a concern and ask a question. While the format is often colloquial, the writers are respected scientists who volunteer commentary against the abuse of science and evidence-based medicine.
Below are science blogs that frequently deal with immunisation issues.